gralloc: Add support for 8-bit RAW MIPI stream

Define new HAL color format for RAW-8 stream and
add support for buffer allocation with RAW-8 format.

Change-Id: I1ee1dbd270d25c27e52c5dd023345c8283c658d2
diff --git a/libgralloc/gralloc_priv.h b/libgralloc/gralloc_priv.h
index 5782180..6f42ac2 100644
--- a/libgralloc/gralloc_priv.h
+++ b/libgralloc/gralloc_priv.h
@@ -120,6 +120,7 @@
 #define HAL_PIXEL_FORMAT_YCbCr_420_P010          0x11F
 #define HAL_PIXEL_FORMAT_CbYCrY_422_I            0x120
 #define HAL_PIXEL_FORMAT_BGR_888                 0x121
+#define HAL_PIXEL_FORMAT_RAW8                    0x123
 
 #define HAL_PIXEL_FORMAT_INTERLACE               0x180