MIPS: tlbex: Remove cpu_has_local_ebase

The cpu_has_local_ebase macro is, confusingly, not used to indicate
whether the EBase register is local to a CPU or not. Instead it
indicates whether we want to generate the TLB refill exception vector
each time a CPU is brought online. Doing this makes little sense on any
system, since we always use the same value for EBase & thus we cannot
have different TLB refill exception handlers per CPU.

Regenerating the code is not only pointless but also can be actively
harmful, as commit 8759934e ("MIPS: Build uasm-generated code only
once to avoid CPU Hotplug problem") described. That commit introduced
cpu_has_local_ebase to disable the handler regeneration for Loongson
machines, but this is by no means a Loongson-specific problem.

Remove cpu_has_local_ebase & simply generate the TLB refill handler once
during boot, just like the rest of the TLB exception handlers.

Signed-off-by: Paul Burton <paul.burton@mips.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Cc: linux-mips@vger.kernel.org