nds32: Avoid accessing beyond the operands[] array

nds32: Avoid accessing beyond the operands[] array

This pattern used operands[2] to hold the shift amount, even though
the pattern doesn't have an operand 2 (not even as a match_dup).
This caused a build failure with -Werror:

  array subscript 2 is above array bounds of ‘rtx_def* [2]’

gcc/
	PR target/100837
	* config/nds32/nds32-intrinsic.md (unspec_get_pending_int): Use
	a local variable instead of operands[2].