MIPS/BFD: Remove extraneous undefined weak symbol visibility check

Remove an extraneous symbol visibility check made for undefined weak
symbols in determination whether an R_MIPS_REL32 dynamic relocation has
to be placed in output, complementing commit ad951203 ("mips: Check
UNDEFWEAK_NO_DYNAMIC_RELOC").  That check duplicates one already made by
the UNDEFWEAK_NO_DYNAMIC_RELOC macro as a part of a broader condition
used to decide if to enter undefined weak symbols to the dynamic symbol
table or not.

	bfd/
	* elfxx-mips.c (allocate_dynrelocs): Remove extraneous symbol
	visibility check made for undefined weak symbols.