MIPS: Loongson: Add GCC 4.4 support for Loongson2E
Because only gcc >=4.4 have loongson-specific support, we need to choose
the suitable -march argument for gcc <= 4.3 and gcc >= 4.4, and here, we
use -march=loongson2e for loongson2e.
Thanks goes to Arnaud Patard <apatard@mandriva.com> for suggestion of
using cc-options(Documentation/kbuild/makefiles.txt). and thanks Zhang
Le for introducing the new CPU_LOONGSON2E kernel option.
NOTE: -mtune option is not need if -march and -mtune use the same value.