powerpc/configs: Drop CONFIG_SERIAL_TXX9_* from cell/ppc64

In commit bf4981a0 ("powerpc: Remove the celleb support") we
dropped the celleb support, which made these symbols unselectable
because we no longer select HAS_TX99_SERIAL. So drop them from the
defconfigs.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/configs/cell_defconfig

@@ -147,8 +147,6 @@ CONFIG_SPIDER_NET=y
 CONFIG_SERIAL_NONSTANDARD=y
 CONFIG_SERIAL_8250=y
 CONFIG_SERIAL_8250_CONSOLE=y
-CONFIG_SERIAL_TXX9_NR_UARTS=2
-CONFIG_SERIAL_TXX9_CONSOLE=y
 CONFIG_SERIAL_OF_PLATFORM=y
 CONFIG_HVC_RTAS=y
 CONFIG_IPMI_HANDLER=m

arch/powerpc/configs/ppc64_defconfig

@@ -192,7 +192,6 @@ CONFIG_INPUT_PCSPKR=m
 CONFIG_SERIAL_8250=y
 CONFIG_SERIAL_8250_CONSOLE=y
 CONFIG_SERIAL_ICOM=m
-CONFIG_SERIAL_TXX9_CONSOLE=y
 CONFIG_SERIAL_JSM=m
 CONFIG_HVC_CONSOLE=y
 CONFIG_HVC_RTAS=y