ARM: riscpc: enable chained scatterlist support

There's no reason why we can't enable chained scatterlist for RiscPC,
we already support chained scatterlists in the IOMD DMA support code.

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

arch/arm/Kconfig

@@ -528,6 +528,7 @@ config ARCH_RPC
 	select ARCH_ACORN
 	select ARCH_MAY_HAVE_PC_FDC
 	select ARCH_SPARSEMEM_ENABLE
+	select ARM_HAS_SG_CHAIN
 	select CPU_SA110
 	select FIQ
 	select HAVE_IDE