[IA64] Remove the useless big endian stuff.

[IA64] Remove the useless big endian stuff.

This patch removes all the useless big endian stuff from the mini-os.
Before there was an effort to support big endian for PV-guest.
But the big endian support was never gotten into the common parts of
the mini-os so it makes no sense to have this only in the ia64
specific sources. And as there is no open source big endian os and
porting our BS2000 os to ia64 was stopped, nobody wants that stuff
in the common minos.
So this looks ugly then and remove the big endian stuff.

Signed-off-by: Dietmar Hahn <dietmar.hahn@fujitsu-siemens.com>