common: Kconfig: Add BMP configs

Add CONFIG_BMP and CONFIG_SPL_BMP which enable displaying bmp images at
u-boot proper and SPL.

Signed-off-by: Nikhil M Jain <n-jain1@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Devarsh Thakkar <devarsht@ti.com>