gralloc: Remove default color space in AllocateBuffer()

The color space should be set explicitly by the producers, not
set by default in gralloc. This change resolves CTS failures in
CtsMediaV2TestCases#EncoderColorAspectsTest.

CRs-Fixed: 2737311
Change-Id: Ia7c780ecc83af3ec742a810de6253fddcfdf66b8
1 file changed