Rewrite the Bathroom Epiphanies Frosty Flake matrix and LED handling (#8243)

* Keyboard: revamp frosty-flake leds

This commit transitions bpiphany/frosty_flake to led_update_{kb,user}
and rewrites the AVR bit twiddling logic to use the standard QMK GPIO
API.

* Keyboard: rewrite frosty_flake's matrix reader to be a lite custom matrix

This commit replaces frosty_flake's custom matrix and debounce logic
with a "lite" custom matrix. In addition to being somewhat clearer, this
allows a consumer of the flake board to choose their own debouncing
algorithm. The one closest to the implementation originally in use is
sym_g, but this opens us up to supporting eager_pk and eager_pr.

The original matrix code was 18 columns for 8 rows, but using a single
row read and unpacking the bits into individual columns. To simplify,
I've changed the key layout to be 8C 18R instead of 18C 8R: this lets us
use a single read directly into the matrix _and_ drop down to a uint8_t
instead of a uint32_t for matrix_row_t.

Since we're no longer implementing our own debouncing and row unpacking,
we save ~400 bytes on the final firmware image.

Fully tested against a CM Storm QFR hosting the flake -- this commit
message was written using the new matrix code.

Firmware Sizes (assuming stock configuration as of 42d6270f2)

Matrix+Debounce     Size (bytes)
---------------     ------------
original            17740
new + sym_g         17284
new + eager_pr      18106
new + eager_pk      18204

I expect that there are some scanning speed benefits as well.

* Keyboard: update frosty_flake's UNUSED_PINS

* Keyboard: Remove meaningless weak redefinitions from frosty

These are not necessary (and all of them already live somewhere in
Quantum).

1 files changed, 3 insertions, 3 deletions

diff --git a/keyboards/bpiphany/frosty_flake/config.h b/keyboards/bpiphany/frosty_flake/config.h
index 250a1b775..79bc31aec 100644
--- a/keyboards/bpiphany/frosty_flake/config.h
+++ b/keyboards/bpiphany/frosty_flake/config.h
@@ -36,13 +36,13 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 /* key matrix size */
-#define MATRIX_ROWS 8   // Row0 - Row7 in the schematic
-#define MATRIX_COLS 18  // ColA - ColR in the schematic
+#define MATRIX_ROWS 18 // ColA - ColR in the schematic
+#define MATRIX_COLS 8  // Row0 - Row7 in the schematic
 
 /*
  * Keyboard Matrix Assignments
  */
-#define UNUSED_PINS { B0, C4, D3 }
+#define UNUSED_PINS { C0, C1, C2, C3, C4, D2, D7 }
 
 /* Debounce reduces chatter (unintended double-presses) - set 0 if debouncing is not needed */
 #define DEBOUNCE 5