MIPS/GAS: Don't convert RELA JALR relocations on R6

MIPS/GAS: Don't convert RELA JALR relocations on R6

Revert an inadvertent change to make RELA JALR relocations
section-relative on MIPS R6 targets made with commit 7361da2c952e ("Add
support for MIPS R6.").  There is no need to make this a special case
and the comment introduced with the said change clearly indicates this
was not intended.

	gas/
	* config/tc-mips.c (mips_fix_adjustable): Don't convert RELA
	JALR relocations on R6.
	* testsuite/gas/mips/jal-svr4pic-local.d: New test.
	* testsuite/gas/mips/mips1@jal-svr4pic-local.d: New test.
	* testsuite/gas/mips/r3000@jal-svr4pic-local.d: New test.
	* testsuite/gas/mips/micromips@jal-svr4pic-local.d: New test.
	* testsuite/gas/mips/jal-svr4pic-local-n32.d: New test.
	* testsuite/gas/mips/micromips@jal-svr4pic-local-n32.d: New
	test.
	* testsuite/gas/mips/jal-svr4pic-local-n64.d: New test.
	* testsuite/gas/mips/micromips@jal-svr4pic-local-n64.d: New
	test.
	* testsuite/gas/mips/jal-svr4pic-local.s: New test source.
	* testsuite/gas/mips/jal-svr4pic-local-newabi.s: New test
	source.
	* testsuite/gas/mips/mips.exp: Run the new tests.