aarch64: Remove redundant mult patterns

aarch64: Remove redundant mult patterns

Following on from the previous commit to fix up the syntax for
add/sub/adds/subs and friends with a sign/zero-extended operand, this
patch removes the "mult" variants of these patterns which are all
redundant.

This patch removes the following patterns from the AArch64 backend:

 *adds_mul_imm_<mode>
 *subs_mul_imm_<mode>
 *adds_<optab><mode>_multp2
 *subs_<optab><mode>_multp2
 *add_mul_imm_<mode>
 *add_<optab><ALLX:mode>_mult_<GPI:mode>
 *add_<optab><SHORT:mode>_mult_si_uxtw
 *add_<optab><mode>_multp2
 *add_<optab>si_multp2_uxtw
 *add_uxt<mode>_multp2
 *add_uxtsi_multp2_uxtw
 *sub_mul_imm_<mode>
 *sub_mul_imm_si_uxtw
 *sub_<optab><mode>_multp2
 *sub_<optab>si_multp2_uxtw
 *sub_uxt<mode>_multp2
 *sub_uxtsi_multp2_uxtw
 *neg_mul_imm_<mode>2
 *neg_mul_imm_si2_uxtw

Together with the following predicates which were used only by these
patterns:

  aarch64_pwr_imm3
  aarch64_pwr_2_si
  aarch64_pwr_2_di

These patterns are all redundant since multiplications by powers of two
should be represented as shfits outside a (mem).

---

gcc/ChangeLog:

	* config/aarch64/aarch64.md (*adds_mul_imm_<mode>): Delete.
	(*subs_mul_imm_<mode>): Delete.
	(*adds_<optab><mode>_multp2): Delete.
	(*subs_<optab><mode>_multp2): Delete.
	(*add_mul_imm_<mode>): Delete.
	(*add_<optab><ALLX:mode>_mult_<GPI:mode>): Delete.
	(*add_<optab><SHORT:mode>_mult_si_uxtw): Delete.
	(*add_<optab><mode>_multp2): Delete.
	(*add_<optab>si_multp2_uxtw): Delete.
	(*add_uxt<mode>_multp2): Delete.
	(*add_uxtsi_multp2_uxtw): Delete.
	(*sub_mul_imm_<mode>): Delete.
	(*sub_mul_imm_si_uxtw): Delete.
	(*sub_<optab><mode>_multp2): Delete.
	(*sub_<optab>si_multp2_uxtw): Delete.
	(*sub_uxt<mode>_multp2): Delete.
	(*sub_uxtsi_multp2_uxtw): Delete.
	(*neg_mul_imm_<mode>2): Delete.
	(*neg_mul_imm_si2_uxtw): Delete.
	* config/aarch64/predicates.md (aarch64_pwr_imm3): Delete.
	(aarch64_pwr_2_si): Delete.
	(aarch64_pwr_2_di): Delete.