i2c: stm32f7: Remove useless error message

Fix the following coccicheck report:

drivers/i2c/busses/i2c-stm32f7.c:2032:3-10 : platform_get_irq :
line 2032 is redundant because platform_get_irq() already prints an error

Remove dev_err() messages after platform_get_irq() failures.

Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Signed-off-by: Zihao Tang <tangzihao1@hisilicon.com>
Reviewed-by: Alain Volmat <alain.volmat@foss.st.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>