ENGR00224910 IPUv3 fb:Correct logic to check BGR24 for if= option

ENGR00224910 IPUv3 fb:Correct logic to check BGR24 for if= option

This patch corrects the logic to check BGR24 pixel format for
'if=' option in kernel bootup command line of framebuffer.
After applying the patch, users may use 'if=BGR24' to specify
the display data format to be BGR24. For example, 'video=mxcfb0:
dev=lcd,LCD_VIDEO_NAME,if=BGR24' makes IPUv3 output BGR24 data
to fb0's lcd panel.

Signed-off-by: Liu Ying <Ying.Liu@freescale.com>
(cherry picked from commit 7ab85674f63eb1388e44a61e17891f0e283c409a)