i2c: designware: Suppress error message if platform_get_irq() < 0

With -EPROBE_DEFER, this message is confusing and we hope for a
centralized printout in the future anyhow.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Acked-by: Christian Ruppert <christian.ruppert@alitech.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>