aarch64: Fix testcase gcc.target/aarch64/insv_1.c

aarch64: Fix testcase gcc.target/aarch64/insv_1.c

There are three failures in gcc.target/aarch64/insv_1.c.
 FAIL: gcc.target/aarch64/insv_1.c scan-assembler bfi\tx[0-9]+, x[0-9]+, 0, 8
 FAIL: gcc.target/aarch64/insv_1.c scan-assembler bfi\tx[0-9]+, x[0-9]+, 16, 5
 FAIL: gcc.target/aarch64/insv_1.c scan-assembler movk\tx[0-9]+, 0x1d6b, lsl 32

This patch fix the third failure which was missed "#" before immediate value
in scan-assembler.

gcc/testsuite/ChangeLog:

	* gcc.target/aarch64/insv_1.c: Add '#' in scan-assembler