Commit 22af89aa0c0b4012a7431114a340efd3665a7617 ("fbcon: replace mono_col
macro with static inline") changed the order of operations for computing
monochrome color values. This generates 0xffff000f instead of 0x0000000f
for a 4 bit monochrome color, leading to image corruption if it is passed
to cfb_imageblit or other similar functions. Fix it up.