gralloc: Set dynamicMetaDataValid for SMPTE2094_40

The dynamicMetaDataValid flag needs to be set or reset in
SetMetadata()  to indicate if the dynamic metadata is useable. This
change was required because GetMetadata() for SMPTE2094_40 was
returning std::nullopt, as the flag was not being set.

CRs-Fixed: 2648631
Change-Id: Ic0dbc6043f94b9848ebf1d17aa81faf9e9754a5e
1 file changed