ARM: 7892/1: Fix warning for V7M builds

Fixes a harmless warning when building for V7M (!MMU):
 arch/arm/kernel/traps.c:859:123: warning: 'kuser_init' defined but not used [-Wunused-function]

By making the stub static inline instead of just static.

Fixes: f6f91b0d ('ARM: allow kuser helpers to be removed from the vector page')
Signed-off-by: NOlof Johansson <olof@lixom.net>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/kernel/traps.c

@@ -856,7 +856,7 @@ static void __init kuser_init(void *vectors)
 		memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
 }
 #else
-static void __init kuser_init(void *vectors)
+static inline void __init kuser_init(void *vectors)
 {
 }
 #endif