PCI: Check for platform_get_irq() failure consistently

The platform_get_irq*() interfaces return either a negative error number or
a valid IRQ.  0 is not a valid return value, so check for "< 0" to detect
failure as recommended by the function documentation.

On failure, return the error number from platform_get_irq*() instead of
making up a new one.

Link: https://lore.kernel.org/r/cover.1583952275.git.amanharitsh123@gmail.com


[bhelgaas: commit log, squash into one patch]
Signed-off-by: Aman Sharma <amanharitsh123@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Cc: Richard Zhu <hongxing.zhu@nxp.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Karthikeyan Mitran <m.karthikeyan@mobiveil.co.in>
Cc: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Ryder Lee <ryder.lee@mediatek.com>
Cc: Marc Gonzalez <marc.w.gonzalez@free.fr>