serial: pxa2xx: remove __deprecated annotation

An otherwise very nice cleanup of the pxa2xx uart support marked the
init function of this driver as __deprecated:

drivers/tty/serial/pxa.c:944:1: error: 'serial_pxa_init' is deprecated [-Werror=deprecated-declarations]

This seems unhelpful to me, as we now warn for every allmodconfig build,
which is otherwise free of warnings on most architectures. Let's
remove the annotation again.

Fixes: ab28f51c ("serial: rewrite pxa2xx-uart to use 8250_core")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>