PCI: Xtensa: convert pcibios_set_master() to a non-inlined function

PCI: Xtensa: convert pcibios_set_master() to a non-inlined function

This patch converts Xtensa's architecture-specific
'pcibios_set_master()' routine to a non-inlined function.  This will
allow follow on patches to create a generic 'pcibios_set_master()'
function using the '__weak' attribute which can be used by all
architectures as a default which, if necessary, can then be over-
ridden by architecture-specific code.

Converting 'pci_bios_set_master()' to a non-inlined function will
allow Xtensa's 'pcibios_set_master()' implementation to remain
architecture-specific after the generic version is introduced and
thus, not change current behavior.

No functional change.

Signed-off-by: Myron Stowe <myron.stowe@redhat.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>