x86: remove duplicate get_bios_ebda() from rio.h

get_bios_ebda() exists in asm/rio.h and asm/bios_ebda.h.
This patch removes the one in asm/rio.h.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>