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

Correct modeling of division instructions in the SIMD/FP domain for
AMD Zen architectures and avoid combinatorial explosion of automaton
tables by modeling the separate floating-point division unit and
correcting reservations to reflect reciprocal throughput of the
corresponding instructions, similar to earlier commit
5cee5f94000 ("i386: correct integer division modeling in znver.md").

Division is partially pipelined and some instructions have fractional
throughput (e.g. Zen 3 can issue divss and divsd each 3.5 and 4.5
cycles on average, respectively). Considering these CPUs implement
out-of-order execution, the model doesn't need to be exact to the last
cycle, so simplify it by using 4/5 cycles for SF/DF modes, and not
modeling the fact that FP3 pipe is occupied for one cycle.

Top znver table sizes in insn-automata.o:

Before:

428108 r znver1_fp_min_issue_delay
856216 r znver1_fp_transitions

After:

30056 r znver1_fp_min_issue_delay
120224 r znver1_fp_transitions

gcc/ChangeLog:

	PR target/87832
	* config/i386/znver.md (znver1_fdiv): New automaton.
	(znver1-fdiv): New unit.
	(znver1_fp_op_div): Correct unit and cycles in the reservation.
	(znver1_fp_op_div_load): Ditto.
	(znver1_fp_op_idiv_load): Ditto.
	(znver2_fp_op_idiv_load): Ditto.
	(znver1_ssediv_ss_ps): Ditto.
	(znver1_ssediv_ss_ps_load): Ditto.
	(znver1_ssediv_sd_pd): Ditto.
	(znver1_ssediv_sd_pd_load): Ditto.
	(znver1_ssediv_avx256_ps): Ditto.
	(znver1_ssediv_avx256_ps_load): Ditto.
	(znver1_ssediv_avx256_pd): Ditto.
	(znver1_ssediv_avx256_pd_load): Ditto.

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