LoongArch: Fix bugs in insn patterns lasx_xvrepl128vei_b/h/w/d_internal

There are two aspects that affect the matching of instruction templates:

1. vec_duplicate is redundant in the following operations.
    set (match_operand:V4DI ...)
	(vec_duplicate:V4DI (vec_select:V4DI ...))

2. The range of values for testing predicate const_8_to_15_operand and
const_16_to_31_operand should be [8, 15] and [16, 31] respectively.

However, there is currently no suitable testcase to verify.

gcc/ChangeLog:

	* config/loongarch/lasx.md: Remove useless vec_select.
	* config/loongarch/predicates.md: Correct error predicate.