[ARM] Fix an rpc_defconfig regression

Fix:

  CC      drivers/scsi/arm/powertec.o
In file included from drivers/scsi/arm/powertec.c:29:
drivers/scsi/arm/scsi.h: In function 'next_SCp':
drivers/scsi/arm/scsi.h:42: error: 'struct scatterlist' has no member named 'page'
drivers/scsi/arm/scsi.h: In function 'init_SCp':
drivers/scsi/arm/scsi.h:80: error: 'struct scatterlist' has no member named 'page'

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>