mfd: intel-lpss: Return error code received from the IRQ API

mfd: intel-lpss: Return error code received from the IRQ API

platform_get_irq() returns a negative error code to indicate an error.
As does pci_alloc_irq_vectors() and pci_irq_vector(). So in
intel_lpss_probe() the erroneous IRQ would be better returned as is.

The pci_alloc_irq_vectors() call and platform_get_irq() guarantee
that IRQs will not be 0, so we'll drop that check as well.

Signed-off-by: Chen Ni <nichen@iscas.ac.cn>
[andy: updated commit message]
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20231106184052.1166579-3-andriy.shevchenko@linux.intel.com
Signed-off-by: Lee Jones <lee@kernel.org>