The md private helper uuid_equal() collides with a generic helper
of the same name.

Rename the md private helper to md_uuid_equal() and do the same for
md_sb_equal().
Signed-off-by: NAmir Goldstein <amir73il@gmail.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NShaohua Li <shli@kernel.org>
Reviewed-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>