Staging: android: lowmemorykiller: fix module param errors

Move module_params to near the end of the source file so that
their references are already known/defined.  Fixes build errors:

drivers/staging/android/lowmemorykiller.c: In function '__check_cost':
drivers/staging/android/lowmemorykiller.c:60: error: 'lowmem_shrinker' undeclared (first use in this function)
drivers/staging/android/lowmemorykiller.c: At top level:
drivers/staging/android/lowmemorykiller.c:60: error: 'lowmem_shrinker' undeclared here (not in a function)
drivers/staging/android/lowmemorykiller.c:60: warning: type defaults to 'int' in declaration of 'type name'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>