[SPARC64]: Fix fault handling in unaligned trap handler.

We were not calling kernel_mna_trap_fault() correctly.
Instead of being fancy, just return 0 vs. -EFAULT from
the assembler stubs, and handle that return value as
appropriate.

Create an "__retl_efault" stub for assembler exception
table entries and use it where possible.

Signed-off-by: David S. Miller <davem@davemloft.net>

include/asm-sparc64/uaccess.h

@@ -77,6 +77,7 @@ struct exception_table_entry {
 };
 
 extern void __ret_efault(void);
+extern void __retl_efault(void);
 
 /* Uh, these should become the main single-value transfer routines..
  * They automatically use the right size if we just have the right