arm: Fix ICE with CMSE nonsecure calls on Armv8.1-M [PR100333]

arm: Fix ICE with CMSE nonsecure calls on Armv8.1-M [PR100333]

As the PR shows, we ICE shortly after expanding nonsecure calls for Armv8.1-M.
For Armv8.1-M, we have TARGET_HAVE_FPCXT_CMSE. As it stands, the expander
(arm.md:nonsecure_call_internal) moves the callee's address to a register (with
copy_to_suggested_reg) only if !TARGET_HAVE_FPCXT_CMSE.

However, looking at the pattern which the insn appears to be intended to
match (thumb2.md:*nonsecure_call_reg_thumb2_fpcxt), it requires the
callee's address to be in a register.

This patch therefore just forces the callee's address into a register in
the expander.

gcc/ChangeLog:

	PR target/100333
	* config/arm/arm.md (nonsecure_call_internal): Always ensure
	callee's address is in a register.

gcc/testsuite/ChangeLog:

	PR target/100333
	* gcc.target/arm/cmse/pr100333.c: New test.