i386: correct x87&SSE multiplication modeling in znver.md

i386: correct x87&SSE multiplication modeling in znver.md

All multiplication instructions are fully pipelined, except AVX256
instructions on Zen 1, which issue over two cycles on a 128-bit unit.
Correct the model accordingly to reduce combinatorial explosion in
automaton tables.

Top znver table sizes in insn-automata.o:

Before:

30056 r znver1_fp_min_issue_delay
120224 r znver1_fp_transitions

After:

6720 r znver1_fp_min_issue_delay
53760 r znver1_fp_transitions

gcc/ChangeLog:

	PR target/87832
	* config/i386/znver.md: (znver1_fp_op_mul): Correct cycles in
	the reservation.
	(znver1_fp_op_mul_load): Ditto.
	(znver1_mmx_mul): Ditto.
	(znver1_mmx_load): Ditto.
	(znver1_ssemul_ss_ps): Ditto.
	(znver1_ssemul_ss_ps_load): Ditto.
	(znver1_ssemul_avx256_ps): Ditto.
	(znver1_ssemul_avx256_ps_load): Ditto.
	(znver1_ssemul_sd_pd): Ditto.
	(znver1_ssemul_sd_pd_load): Ditto.
	(znver2_ssemul_sd_pd): Ditto.
	(znver2_ssemul_sd_pd_load): Ditto.
	(znver1_ssemul_avx256_pd): Ditto.
	(znver1_ssemul_avx256_pd_load): Ditto.
	(znver1_sseimul): Ditto.
	(znver1_sseimul_avx256): Ditto.
	(znver1_sseimul_load): Ditto.
	(znver1_sseimul_avx256_load): Ditto.
	(znver1_sseimul_di): Ditto.
	(znver1_sseimul_load_di): Ditto.