serial: 8250_dw: Avoid double error messaging when IRQ absent

Since the commit 7723f4c5 ("driver core: platform: Add an error message
to platform_get_irq*()") platform_get_irq() started issuing an error message.
Thus, there is no need to have the same in the driver

Fixes: 7723f4c5 ("driver core: platform: Add an error message to platform_get_irq*()")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20191023103558.51862-1-andriy.shevchenko@linux.intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>