tegra_fb: re-enable double-buffering support

Commit 185b396 made
double-buffering support in the fb driver conditional
on CONFIG_ANDROID, but was an incomplete removal of the
feature - userland apps can still set up the device
for double-buffering, since it looks like it still supports
it, but then get EINVAL errors when tryng to use it.

Since the difference in memory is only 32MiB, just remove
the CONFIG_ANDROID check and enable double-buffering
in all builds.

Signed-off-by: Matt Madison <matt@madison.systems>

drivers/video/tegra/fb.c

@@ -56,11 +56,8 @@
 #define user_ptr(p) (p)
 #endif
 
-#ifdef CONFIG_ANDROID
 #define FB_BUFFERING_FACTOR 2
-#else /* L4T and other OSes */
-#define FB_BUFFERING_FACTOR 1
-#endif
+
 /* support up to 4K (3840x2150) with double buffering */
 #define DEFAULT_FBMEM_SIZE	(SZ_32M * FB_BUFFERING_FACTOR) + SZ_8M