i2c: st: Use min() to improve code

i2c: st: Use min() to improve code

Use min() to reduce the code and improve its readability.

The type of the max parameter in the st_i2c_rd_fill_tx_fifo()
was changed from int to u32, because the max parameter passed
in is always greater than 0.

Signed-off-by: Qianfeng Rong <rongqianfeng@vivo.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20250709042347.550993-1-rongqianfeng@vivo.com