i8k: Avoid lahf in 64-bit code

i8k uses lahf to read the flag register in 64-bit code; early x86-64
CPUs, however, lack this instruction and we get an invalid opcode
exception at runtime.
Use pushf to load the flag register into the stack instead.

Signed-off-by: Luca Tettamanti <kronos.it@gmail.com>
Reported-by: Jeff Rickman <jrickman@myamigos.us>
Tested-by: Jeff Rickman <jrickman@myamigos.us>
Tested-by: Harry G McGavran Jr <w5pny@arrl.net>
Cc: stable@kernel.org
Cc: Massimo Dal Zotto <dz@debian.org>
Signed-off-by: Jean Delvare <khali@linux-fr.org>