powerpc/configs/skiroot: Disable xmon default & enable reboot on panic

If the skiroot kernel crashes we don't want it sitting at an xmon
prompt forever. Instead it's more helpful to reboot and bring the
boot loader back up, and if the crash was transient we can then boot
successfully.

Similarly if we panic we should reboot, with a short timeout in case
someone is watching the console.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20200121043000.16212-8-mpe@ellerman.id.au

arch/powerpc/configs/skiroot_defconfig

@@ -29,6 +29,7 @@ CONFIG_ALTIVEC=y
 CONFIG_VSX=y
 CONFIG_NR_CPUS=2048
 CONFIG_CPU_LITTLE_ENDIAN=y
+CONFIG_PANIC_TIMEOUT=30
 # CONFIG_PPC_VAS is not set
 # CONFIG_PPC_PSERIES is not set
 # CONFIG_PPC_OF_BOOT_TRAMPOLINE is not set
@@ -294,6 +295,7 @@ CONFIG_LIBCRC32C=y
 CONFIG_PRINTK_TIME=y
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_DEBUG_STACKOVERFLOW=y
+CONFIG_PANIC_ON_OOPS=y
 CONFIG_SOFTLOCKUP_DETECTOR=y
 CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC=y
 CONFIG_HARDLOCKUP_DETECTOR=y
@@ -302,5 +304,4 @@ CONFIG_WQ_WATCHDOG=y
 # CONFIG_SCHED_DEBUG is not set
 # CONFIG_FTRACE is not set
 CONFIG_XMON=y
-CONFIG_XMON_DEFAULT=y
 # CONFIG_RUNTIME_TESTING_MENU is not set