ARM: alpine: select the Alpine MSI controller driver

Select the Alpine MSI controller driver when using an Alpine platform.

Signed-off-by: Antoine Tenart <antoine.tenart@free-electrons.com>
Signed-off-by: Tsahee Zidenberg <tsahee@annapurnalabs.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>