C2SoftGav1Dec: Disallow bitdepth > 10

This is a temporary change that will be over-written when
support for 12-bit is added.

Bug: 268505204
Test: AV1 and AVIF CTS tests pass
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:f5ac54ffb824588e8109f3ced83a1800a9446a4f)
Merged-In: Ia2ac55bddabfa20046862e5cb1816449ae9429d9
Change-Id: Ia2ac55bddabfa20046862e5cb1816449ae9429d9