uml: tidy process.c

Clean up arch/um/kernel/process.c:

- lots of return(x); -> return x; conversions

- a number of the small functions are either unused, in which case they are
  gone, along any declarations in a header, or could be made static.

- current_pid is ifdefed on CONFIG_MODE_TT and its declaration is ifdefed on
  both CONFIG_MODE_TT and UML_CONFIG_MODE_TT because we don't know whether
  it's being used in a userspace or kernel file.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/um/include/tt/uaccess-tt.h

@@ -27,8 +27,6 @@ extern unsigned long uml_physmem;
 #define access_ok_tt(type, addr, size) \
 	(is_stack(addr, size))
 
-extern unsigned long get_fault_addr(void);
-
 extern int __do_copy_from_user(void *to, const void *from, int n,
 			       void **fault_addr, void **fault_catcher);
 extern int __do_strncpy_from_user(char *dst, const char *src, size_t n,