MIPS/binutils/testsuite: Fix `.dc.l' typo in `strip-13mips64.s'

MIPS/binutils/testsuite: Fix `.dc.l' typo in `strip-13mips64.s'

Fix a typo: `.dc.w' -> `.dc.l' in `strip-13mips64.s', correcting a bug
from commit 2f8ceb38991e ("binutils/testsuite: Support REL and MIPS64
reloc formats with `strip-13'").  For relocation format correctness only
as there is no observable change in test results due to the lack of
connection between the second relocation entry affected and the examined
error message produced.

	binutils/
	* testsuite/binutils-all/strip-13mips64.s: Use `.dc.l' rather
	than `.dc.w' in second relocation.