x86/boot: Fix memory leak in default_get_smp_config()

When default_get_smp_config() is called with early == 1 and mpf->feature1
is non-zero, mpf is leaked because the return path does not do
early_memunmap().

Fix this and share a common exit routine.

Fixes: 5997efb ("x86/boot: Use memremap() to map the MPF and MPC data")
Reported-by: Cfir Cohen <cfir@google.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1907091942570.28240@chino.kir.corp.google.com

arch/x86/kernel/mpparse.c

@@ -546,17 +546,15 @@ void __init default_get_smp_config(unsigned int early)
 			 * local APIC has default address
 			 */
 			mp_lapic_addr = APIC_DEFAULT_PHYS_BASE;
-			return;
+			goto out;
 		}
 
 		pr_info("Default MP configuration #%d\n", mpf->feature1);
 		construct_default_ISA_mptable(mpf->feature1);
 
 	} else if (mpf->physptr) {
-		if (check_physptr(mpf, early)) {
-			early_memunmap(mpf, sizeof(*mpf));
-			return;
-		}
+		if (check_physptr(mpf, early))
+			goto out;
 	} else
 		BUG();
 
@@ -565,7 +563,7 @@ void __init default_get_smp_config(unsigned int early)
 	/*
 	 * Only use the first configuration found.
 	 */
-
+out:
 	early_memunmap(mpf, sizeof(*mpf));
 }