powerpc/pmac32: enable serial options by default in defconfig

Serial is a critical feature for logging and debuging, and the other
architectures enable serial by default.

Let's enable CONFIG_SERIAL_PMACZILOG and CONFIG_SERIAL_PMACZILOG_CONSOLE
by default.
Signed-off-by: Yuan Tan <tanyuan@tinylab.org>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/bb7b5f9958b3e3a20f6573ff7ce7c5dc566e7e32.1690982937.git.tanyuan@tinylab.org

arch/powerpc/configs/pmac32_defconfig

@@ -176,8 +176,9 @@ CONFIG_MOUSE_APPLETOUCH=y
 # CONFIG_SERIO_I8042 is not set
 # CONFIG_SERIO_SERPORT is not set
 CONFIG_SERIAL_8250=m
-CONFIG_SERIAL_PMACZILOG=m
+CONFIG_SERIAL_PMACZILOG=y
 CONFIG_SERIAL_PMACZILOG_TTYS=y
+CONFIG_SERIAL_PMACZILOG_CONSOLE=y
 CONFIG_NVRAM=y
 CONFIG_I2C_CHARDEV=m
 CONFIG_APM_POWER=y