spi/mpc8xxx: don't check platform_get_irq's return value against zero
spi/mpc8xxx: don't check platform_get_irq's return value against zero

platform_get_irq returns -ENXIO on failure, so !irq was probably
always true.  Make irq a signed variable and compare irq <= 0.  Note
that a return value of zero is still handled as error even though this
could mean irq0.

This is a followup to 305b3228f9ff4d59f49e6d34a7034d44ee8ce2f0 that
changed the return value of platform_get_irq from 0 to -ENXIO on error.

Signed-off-by: Uwe Kleine-König <181323dd666a182bc2d953e52d0ac3ab54cd8391@pengutronix.de>
Acked-by: Anton Vorontsov <f72eea26502475052d15bdce621d2155da84f214@ru.mvista.com>
Signed-off-by: Grant Likely <9069e6f5a2b566e2674a0ba1e2bf39c12c195fad@secretlab.ca>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs