Use ANDROID_NATIVE_UNSIGNED_CAST() in GraphicBufferMapper::lockAsync()

If bit 31 of the return value of android_convertGralloc1To0Usage() is 1,
the high 32 bits of "usage" is all 1.
To fix, add ANDROID_NATIVE_UNSIGNED_CAST().

Change-Id: I501c5dd66ee3f3a25269b5eb6e5d74c05cf44c79
Merged-In: Ib4590b7a3b839a993f6c747c5f09a6312f7ab329
Signed-off-by: Fang Hui <hui.fang@nxp.com>