MIPS: Delete unused flush_cache_sigtramp()

Commit adcc81f148 ("MIPS: math-emu: Write-protect delay slot emulation
pages") left flush_cache_sigtramp() unused. Delete the dead code.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: linux-mips@vger.kernel.org

arch/mips/mm/cache.c

@@ -47,7 +47,6 @@ void (*__flush_kernel_vmap_range)(unsigned long vaddr, int size);
 EXPORT_SYMBOL_GPL(__flush_kernel_vmap_range);
 
 /* MIPS specific cache operations */
-void (*flush_cache_sigtramp)(unsigned long addr);
 void (*local_flush_data_cache_page)(void * addr);
 void (*flush_data_cache_page)(unsigned long addr);
 void (*flush_icache_all)(void);