i2c: imx: propagate irq error code in probe

smatch rightfully says:
drivers/i2c/busses/i2c-imx.c:610 i2c_imx_probe() info: why not propagate 'irq' from platform_get_irq() instead of (-2)?

Signed-off-by: Wolfram Sang <wsa@the-dreams.de>