usb_charge: drop USB_CHG_TASK_COUNT
usb_charge: drop USB_CHG_TASK_COUNT

USB_CHG_TASK_COUNT is not used anywhere, drop it.

BRANCH=none
BUG=none
TEST=zmake testall

Signed-off-by: Fabio Baltieri <1c55e39c05d9ab42261288cf330256b2af6ba179@google.com>
Change-Id: Ia7fb4d0bbcdb6b6edaea1be96a0d5ada43bbcfba
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3661581
Reviewed-by: Aaron Massey <79529a820df71f45023239a3663736629646cc34@google.com>

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