kernel: fix several implicit usasges of kmod.h

These files were implicitly relying on <linux/kmod.h> coming in via
module.h, as without it we get things like:

kernel/power/suspend.c💯 error: implicit declaration of function ‘usermodehelper_disable’
kernel/power/suspend.c:109: error: implicit declaration of function ‘usermodehelper_enable’
kernel/power/user.c:254: error: implicit declaration of function ‘usermodehelper_disable’
kernel/power/user.c:261: error: implicit declaration of function ‘usermodehelper_enable’

kernel/sys.c:317: error: implicit declaration of function ‘usermodehelper_disable’
kernel/sys.c:1816: error: implicit declaration of function ‘call_usermodehelper_setup’
kernel/sys.c:1822: error: implicit declaration of function ‘call_usermodehelper_setfns’
kernel/sys.c:1824: error: implicit declaration of function ‘call_usermodehelper_exec’

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

kernel/power/user.c

@@ -12,6 +12,7 @@
 #include <linux/suspend.h>
 #include <linux/syscalls.h>
 #include <linux/reboot.h>
+#include <linux/kmod.h>
 #include <linux/string.h>
 #include <linux/device.h>
 #include <linux/miscdevice.h>