x86-64, trampoline: Remove unused variable

Removed unused variable left over from development.
Reported-by: Brian Gerst <brgerst@gmail.com>
LKML-Reference: <AANLkTik6UJ680mWJcu_W+jerLcqPjwjvaXyxB1jAMaG0@mail.gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Matthieu Castet <castet.matthieu@free.fr>

arch/x86/kernel/trampoline_64.S

@@ -157,8 +157,6 @@ startup_64_vector:
 	.word	__KERNEL_CS, 0
 
 	.balign 4
-fixup_base:
-	.long	0
 ENTRY(trampoline_status)
 	.long	0