In acpi_table_parse(), pointer of the table to pass to handler() is
checked before handler() called, so remove all the duplicate NULL
check in the handler function.

CC: Tony Luck <tony.luck@intel.com>
CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: NHanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>