Use makedev helper for device major and minor numbers

Major and minor numbers can be greater than 255.  Major numbers
are 12 bits, and minor numbers are 20 bits.  Supporting major
and minor numbers > 255 allows the use of the extended block
device for extra mmc partitions.

Change-Id: I4c42bfe0781069e8e4cb13ebe26e860cdc03f866
1 file changed