target/ppc: Move multiply fixed-point insns (64-bit operands) to decodetree.

target/ppc: Move multiply fixed-point insns (64-bit operands) to decodetree.

Moving the following instructions to decodetree :

	mul{ld, ldo, hd, hdu}[.]	: XO-form
	madd{hd, hdu, ld}		: VA-form

The changes were verified by validating that the tcg ops generated by those
instructions remain the same, which were captured with the '-d in_asm,op'
flag.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Chinmay Rath <rathc@linux.ibm.com>
[np: 32-bit compile fix]
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>