ASoC: stm: stm32_i2s: Fix calc_clk_div() error handling in determine_rate()

calc_clk_div() will only return a non-zero value (-EINVAL)
in case of error. On the other hand, req->rate is an unsigned long.
It seems quite odd that req->rate would be assigned a negative value,
which is clearly not a rate, and success would be returned.

Reinstate previous logic, which would just return error.

Fixes: afd529d7 ("ASoC: stm: stm32_i2s: convert from round_rate() to determine_rate()")
Link: https://scan7.scan.coverity.com/#/project-view/53936/11354?selectedIssue=1647702



Signed-off-by: Sergio Perez Gonzalez <sperezglz@gmail.com>
Link: https://patch.msgid.link/20250729020052.404617-1-sperezglz@gmail.com


Signed-off-by: Mark Brown <broonie@kernel.org>