xtensa: uaccess: Add missing __user to strncpy_from_user() prototype

When adding __user annotations in commit 2adf5352, the
strncpy_from_user() function declaration for the
CONFIG_GENERIC_STRNCPY_FROM_USER case was missed. Fix it.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Message-Id: <20200831210937.17938-1-laurent.pinchart@ideasonboard.com>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/include/asm/uaccess.h

@@ -302,7 +302,7 @@ strncpy_from_user(char *dst, const char __user *src, long count)
 	return -EFAULT;
 }
 #else
-long strncpy_from_user(char *dst, const char *src, long count);
+long strncpy_from_user(char *dst, const char __user *src, long count);
 #endif
 
 /*