powerpc/mce: Move 64-bit machine check code into mce.c

powerpc/mce: Move 64-bit machine check code into mce.c

BugLink: http://bugs.launchpad.net/bugs/1721070
We already have mce.c which is built for 64bit and contains other parts
of the machine check code, so move these bits in there too.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
(cherry picked from commit ccd3cd361341b71ae2afa596f6b470fcb32a916e)
Signed-off-by: Joseph Salisbury <joseph.salisbury@canonical.com>
Acked-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>