ARM: Fix IXP23xx build error in mach/memory.h

One to many close parens.

In file included from arch/arm/include/asm/page.h:202,
                 from include/linux/mm_types.h:15,
                 from include/linux/sched.h:63,
                 from arch/arm/kernel/asm-offsets.c:13:
arch/arm/include/asm/memory.h: In function 'virt_to_bus':
arch/arm/include/asm/memory.h:214: error: expected ';' before ')' token
arch/arm/include/asm/memory.h:214: error: expected statement before ')' token
arch/arm/include/asm/memory.h: In function 'bus_to_virt':
arch/arm/include/asm/memory.h:219: error: expected ';' before ')' token
arch/arm/include/asm/memory.h:219: error: expected statement before ')' token

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