Revert "linux/defconfig: Set ipr.fast_reboot=1"

This reverts commit e920f5dedb75e5c3f451c3607ea016f3fef2961c:
(linux/defconfig: Set ipr.fast_reboot=1)

This setting is not currently compatible with Simics p10

Conflicts:
	openpower/configs/linux/skiroot_p9_defconfig
        (no longer exists)
diff --git a/openpower/configs/linux/skiroot_defconfig b/openpower/configs/linux/skiroot_defconfig
index d0cda0e..2fb25a8 100644
--- a/openpower/configs/linux/skiroot_defconfig
+++ b/openpower/configs/linux/skiroot_defconfig
@@ -46,7 +46,7 @@
 CONFIG_PPC_64K_PAGES=y
 CONFIG_SCHED_SMT=y
 CONFIG_CMDLINE_BOOL=y
-CONFIG_CMDLINE="console=tty0 console=hvc0 ipr.fast_reboot=1 quiet"
+CONFIG_CMDLINE="console=tty0 console=hvc0 quiet"
 # CONFIG_SECCOMP is not set
 # CONFIG_PPC_MEM_KEYS is not set
 CONFIG_JUMP_LABEL=y