s390: Increment PC-relative relocation count for PC24DBL relocs

s390: Increment PC-relative relocation count for PC24DBL relocs

Commit fb798c50b2c8 added the R_390_PC24DBL relocation.  Due to a copy
and paste error it messed up to increment the PC-relative relocation
count in elf64-s390.c function elf_s390_check_relocs (i.e. duplicate
check for R_390_PC16DBL).

Found while inspecting and cleaning up differences between elf32-s390.c
and elf64-s390.c.

bfd/
	* elf64-s390.c (elf_s390_check_relocs): Increment PC-relative
	relocation count for R_390_PC24DBL.

Fixes: fb798c50b2c8
Signed-off-by: Jens Remus <jremus@linux.ibm.com>