init/main.c: include <linux/mem_encrypt.h>

In commit c775320 ("x86, swiotlb: Add memory encryption support") a
call to function `mem_encrypt_init' was added.  Include prototype
defined in header <linux/mem_encrypt.h> to prevent a warning reported
during compilation with W=1:

  init/main.c:494:20: warning: no previous prototype for `mem_encrypt_init' [-Wmissing-prototypes]

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Mathieu Malaterre <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Acked-by: Steven Rostedt (VMware) <[email protected]>
Cc: Tom Lendacky <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Laura Abbott <[email protected]>
Cc: Dominik Brodowski <[email protected]>
Cc: Gargi Sharma <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

init/main.c

@@ -91,6 +91,7 @@
 #include <linux/cache.h>
 #include <linux/rodata_test.h>
 #include <linux/jump_label.h>
+#include <linux/mem_encrypt.h>
 
 #include <asm/io.h>
 #include <asm/bugs.h>