scripts/gdb: add lx-genpd-summary command

This is like /sys/kernel/debug/pm/pm_genpd_summary except it's
accessible through a debugger.

This can be useful if the target crashes or hangs because power domains
were not properly enabled.

Link: http://lkml.kernel.org/r/f9ee627a0d4f94b894aa202fee8a98444049bed8.1561492937.git.leonard.crestez@nxp.com
Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
Reviewed-by: Stephen Boyd <sboyd@kernel.org>
Cc: Kieran Bingham <kbingham@kernel.org>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/scripts/gdb/vmlinux-gdb.py b/scripts/gdb/vmlinux-gdb.py
index eff5a48..a504f51 100644
--- a/scripts/gdb/vmlinux-gdb.py
+++ b/scripts/gdb/vmlinux-gdb.py
@@ -35,3 +35,4 @@
     import linux.constants
     import linux.timerlist
     import linux.clk
+    import linux.genpd