The uapi header file listed in the cxlflash stanza has a typo.

Removed the trailing 's' from the filename.
Reported-by: NJoe Perches <joe@perches.com>
Signed-off-by: NMatthew R. Ochs <mrochs@linux.ibm.com>
Acked-by: NUma Krishnan <ukrishn@linux.ibm.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>