x86/realmode: Make set_real_mode_mem() static inline

Remove the unused @size argument and move it into a header file, so it
can be inlined.

 [ bp: Massage. ]

Signed-off-by: Matteo Croce <mcroce@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Mukesh Ojha <mojha@codeaurora.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-efi <linux-efi@vger.kernel.org>
Cc: platform-driver-x86@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190328114233.27835-1-mcroce@redhat.com

arch/x86/realmode/init.c

@@ -15,13 +15,6 @@ u32 *trampoline_cr4_features;
 /* Hold the pgd entry used on booting additional CPUs */
 pgd_t trampoline_pgd_entry;
 
-void __init set_real_mode_mem(phys_addr_t mem, size_t size)
-{
-	void *base = __va(mem);
-
-	real_mode_header = (struct real_mode_header *) base;
-}
-
 void __init reserve_real_mode(void)
 {
 	phys_addr_t mem;
@@ -40,7 +33,7 @@ void __init reserve_real_mode(void)
 	}
 
 	memblock_reserve(mem, size);
-	set_real_mode_mem(mem, size);
+	set_real_mode_mem(mem);
 }
 
 static void __init setup_real_mode(void)