x86/asm/entry/64: Shrink code in 'paranoid_exit'

x86/asm/entry/64: Shrink code in 'paranoid_exit'

RESTORE_EXTRA_REGS + RESTORE_C_REGS looks small, but it's
a lot of instructions (fourteen). Let's reuse them.

Signed-off-by: Denys Vlasenko <[email protected]>
[ Cleaned up the labels. ]
Signed-off-by: Andy Lutomirski <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Will Drewry <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/59d71848cee3ec9eb48c0252e602efd6bd560e3c.1424989793.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <[email protected]>