OpenRISC does not have global memory_start and memory_end
symbols.
The prototypes are in vain.
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Jonas Bonn <jonas@southpole.se>
virt_addr_valid() shouldn't be comparing the address to memory_end which is
a phys_addr_t. Change this to do like other arches and check that the
address falls within a valid page frame.
Signed-off-by: Jonas Bonn <jonas@southpole.se>