Fix section mismatch in spi-pl022.c

WARNING: drivers/spi/built-in.o(.devinit.text+0xdb8): Section mismatch in reference from the function pl022_probe() to the function .init.text:pl022_dma_probe()
The function __devinit pl022_probe() references
a function __init pl022_dma_probe().
If pl022_dma_probe is only used by pl022_probe then
annotate pl022_dma_probe with a matching annotation.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>