zephyr: brya: usb_mux: Split struct usb_mux in brya board
zephyr: brya: usb_mux: Split struct usb_mux in brya board

Update brya board to use new struct usb_mux_chain.

BUG=b:236274003
TEST=zmake build -a
TEST=./twister -T zephyr/test
BRANCH=None

Cq-Depend: chromium:3779618
Signed-off-by: Tomasz Michalec <a547db31280d14f095c760a23a7523d0b1e55fe6@semihalf.com>
Change-Id: Icccb0299cea28c21656ab2faf8dac10309ae07ea
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3780418
Tested-by: Tomasz Michalec <c064a6042954d4ba0805003dc021b76413ff1548@google.com>
Reviewed-by: Keith Short <f6d578f97033c25f1206cb57d52f358974c82954@chromium.org>
Commit-Queue: Tomasz Michalec <c064a6042954d4ba0805003dc021b76413ff1548@google.com>

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