stm32/usb_hid_keyboard; implement new top row keys
stm32/usb_hid_keyboard; implement new top row keys

Use the hid usage mapping from drivers/hid/hid-input.c:

    Page 0xB, Usage 0x2F -> KEY_MICMUTE
    Page 0xC, Usage 0x7C -> KEY_KBDILLUMTOGGLE

BUG=b:194460146
TEST=Map the new keys to F1/F2 on homestar, and verify
     1) kernal can get the expected key code.
       Event: -------------- SYN_REPORT ------------
       Event: type 4 (EV_MSC), code 4 (MSC_SCAN), value b002f
       Event: type 1 (EV_KEY), code 248 (KEY_MICMUTE), value 1
       Event: -------------- SYN_REPORT ------------
       Event: type 4 (EV_MSC), code 4 (MSC_SCAN), value b002f
       Event: type 1 (EV_KEY), code 248 (KEY_MICMUTE), value 0
       Event: -------------- SYN_REPORT ------------
       Event: type 4 (EV_MSC), code 4 (MSC_SCAN), value c007c
       Event: type 1 (EV_KEY), code 228 (KEY_KBDILLUMTOGGLE), value 1
       Event: -------------- SYN_REPORT ------------
       Event: type 4 (EV_MSC), code 4 (MSC_SCAN), value c007c
       Event: type 1 (EV_KEY), code 228 (KEY_KBDILLUMTOGGLE), value 0
     2) `cat /sys/class/input/*/device/function_row_physmap`
BRANCH=trogdor

Signed-off-by: Ting Shen <c671d3efec3d7e7e285f3788bf0d1ba4c8605b78@google.com>
Change-Id: Ibf342b881ee428598adaeb73a63bf242cd220004
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3073440
Reviewed-by: Wai-Hong Tam <04b587fdf5845741a0c5a8b9cd59ca72d73ef8fc@google.com>
Commit-Queue: Ting Shen <c671d3efec3d7e7e285f3788bf0d1ba4c8605b78@chromium.org>
Tested-by: Ting Shen <c671d3efec3d7e7e285f3788bf0d1ba4c8605b78@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec