Fix aarch64_evpc_tbl guard (PR 85910)

Fix aarch64_evpc_tbl guard (PR 85910)

This patch fixes a typo in aarch64_expand_vec_perm_const_1 that I
introduced as part of the SVE changes.  I don't know of any cases in
which it has any practical effect, since we'll eventually try to use
TBL as a variable permute instead.  Having the code is still an
important part of defining the interface properly and so we shouldn't
simply drop it.

2018-08-23  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	PR target/85910
	* config/aarch64/aarch64.c (aarch64_expand_vec_perm_const_1): Fix
	aarch64_evpc_tbl guard.

From-SVN: r263803