Remove RGBX_FP16 format

Bug: 32984164
Test: compile
Change-Id: I5fb298c7020b9e09bbec041088b296e315e9bec4
diff --git a/include/system/graphics-base.h b/include/system/graphics-base.h
index 82d077c..346a318 100644
--- a/include/system/graphics-base.h
+++ b/include/system/graphics-base.h
@@ -15,7 +15,6 @@
     HAL_PIXEL_FORMAT_RGB_565 = 4,
     HAL_PIXEL_FORMAT_BGRA_8888 = 5,
     HAL_PIXEL_FORMAT_RGBA_FP16 = 22, // 0x16
-    HAL_PIXEL_FORMAT_RGBX_FP16 = 23, // 0x17
     HAL_PIXEL_FORMAT_YV12 = 842094169, // 0x32315659
     HAL_PIXEL_FORMAT_Y8 = 538982489, // 0x20203859
     HAL_PIXEL_FORMAT_Y16 = 540422489, // 0x20363159