staging: vc04_services: fix dmac_map/unmap_area prototypes

You don't define a function prototype on one line as a #define, and then
the next declare it as an external C function, without expecting a C
compiler to complain loudly.

So fix up this mess.

Cc: Daniel Stone <daniels@collabora.com>
Cc: "Noralf Trønnes" <noralf@tronnes.org>
Cc: Pranith Kumar <bobby.prani@gmail.com>
Cc: popcornmix <popcornmix@gmail.com>
Cc: Eric Anholt <eric@anholt.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c

@@ -48,9 +48,6 @@
 #define dmac_map_area			__glue(_CACHE,_dma_map_area)
 #define dmac_unmap_area 		__glue(_CACHE,_dma_unmap_area)
 
-extern void dmac_map_area(const void *, size_t, int);
-extern void dmac_unmap_area(const void *, size_t, int);
-
 #define TOTAL_SLOTS (VCHIQ_SLOT_ZERO_SLOTS + 2 * 32)
 
 #define VCHIQ_ARM_ADDRESS(x) ((void *)((char *)x + g_virt_to_bus_offset))