erofs: cleanup i_format-related stuffs

Switch EROFS_I_{VERSION,DATALAYOUT}_BITS into
EROFS_I_{VERSION,DATALAYOUT}_MASK.

Also avoid erofs_bitrange() since its functionality is simple enough.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20230414083027.12307-2-hsiangkao@linux.alibaba.com