[MIPS] IP27, IP35: Fix warnings.

[MIPS] IP27, IP35: Fix warnings.

include/asm-mips/mach-ip27/dma-coherence.h:22: warning: 'plat_map_dma_mem' defined but not used
include/asm-mips/mach-ip27/dma-coherence.h:41: warning: 'plat_unmap_dma_mem' defined but not used
include/asm-mips/mach-ip32/dma-coherence.h:30: warning: 'plat_map_dma_mem' defined but not used
include/asm-mips/mach-ip32/dma-coherence.h:63: warning: 'plat_unmap_dma_mem' defined but not used

These functions are meant to be inlined anyway.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>