MIPS: Fix build for LTS kernel caused by backporting lpj adjustment

Commit ed26aacfb5f71eecb20a ("mips: Add udelay lpj numbers adjustment")
has backported to 4.4~5.4, but the "struct cpufreq_freqs" (and also the
cpufreq notifier machanism) of 4.4~4.19 are different from the upstream
kernel. These differences cause build errors, and this patch can fix the
build.

Cc: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Cc: Stable <stable@vger.kernel.org> # 4.4/4.9/4.14/4.19
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>