arm: mve: Don't force trivial vector literals to the pool

arm: mve: Don't force trivial vector literals to the pool

A bug in the ordering of the operands in the mve_mov<mode> pattern
meant that all literal values were being pushed to the literal pool.
This patch fixes that and simplifies some of the logic slightly so
that we can use as simple switch statement.

For example:
void f (uint32_t *a)
{
  int i;
  for (i = 0; i < 100; i++)
    a[i] += 1;
}

Now compiles to:
        push    {lr}
        mov     lr, #25
        vmov.i32        q2, #0x1  @ v4si
        ...

instead of

        push    {lr}
        mov     lr, #25
        vldr.64 d4, .L6
        vldr.64 d5, .L6+8
	...
.L7:
        .align  3
.L6:
        .word   1
        .word   1
        .word   1
        .word   1

gcc/ChangeLog:
	* config/arm/mve.md (*mve_mov<mode>): Re-order constraints
	to avoid spilling trivial literals to the constant pool.

gcc/testsuite/ChangeLog:
	* gcc.target/arm/acle/cde-mve-full-assembly.c: Adjust expected
	output.