arm64: Only select ARM64_MODULE_PLTS if MODULES=y

Selecting CONFIG_RANDOMIZE_BASE=y and CONFIG_MODULES=n fails to build
the module PLTs support:

  CC      arch/arm64/kernel/module-plts.o
/work/Linux/linux-2.6-aarch64/arch/arm64/kernel/module-plts.c: In function ‘module_emit_plt_entry’:
/work/Linux/linux-2.6-aarch64/arch/arm64/kernel/module-plts.c:32:49: error: dereferencing pointer to incomplete type ‘struct module’

This patch selects ARM64_MODULE_PLTS conditionally only if MODULES is
enabled.

Fixes: f80fb3a3d508 ("arm64: add support for kernel ASLR")
Cc: <stable@vger.kernel.org> # 4.6+
Reported-by: Jeff Vander Stoep <jeffv@google.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
(cherry picked from commit b9c220b589daaf140f5b8ebe502c98745b94e65c)
Signed-off-by: Alex Shi <alex.shi@linaro.org>

Author: ctmarinas

arch/arm64/Kconfig

@@ -750,7 +750,7 @@ config RELOCATABLE
 
 config RANDOMIZE_BASE
 	bool "Randomize the address of the kernel image"
-	select ARM64_MODULE_PLTS
+	select ARM64_MODULE_PLTS if MODULES
 	select RELOCATABLE
 	help
 	  Randomizes the virtual address at which the kernel image is