build.config: Remove IN_KERNEL_MODULES if no modules

The two defconfig files mnh_prod_defconfig and mnh_qemu_defconfig don't
have CONFIG_MODULES enabled.  Make respective changes in build.config.

Without this change, we are seeing the following error message when
running "make modules_install"

The present kernel configuration has modules disabled.
Type 'make config' and enable loadable module support.
Then build a kernel with module support enabled.

make[2]: *** [modules_install] Error 1
make[1]: *** [sub-make] Error 2
make: *** [__sub-make] Error 2

Change-Id: I72654f320169795209597795cb3ef4525c791911
Signed-off-by: Daniel Mentz <danielmentz@google.com>
diff --git a/build.config b/build.config
index 9f6e2f0..1d5f99a 100644
--- a/build.config
+++ b/build.config
@@ -11,4 +11,3 @@
 vmlinux
 System.map
 "
-IN_KERNEL_MODULES=1
diff --git a/build.config.qemu b/build.config.qemu
index 2e6b68d..dbf3be8 100644
--- a/build.config.qemu
+++ b/build.config.qemu
@@ -11,4 +11,3 @@
 vmlinux
 System.map
 "
-IN_KERNEL_MODULES=1