clk: tegra124: Remove lock-enable bit from PLLM

According to the Tegra124 TRM documentation, PLLM_MISC2 register doesn't
have the lock-enable bit as well as any other PLLM-related register. Hence
PLLM re-locking can't be initiated by software. The incorrect bit setting
should have been harmless since that bit is undefined according to TRM.

Tested-by: Steev Klimaszewski <steev@kali.org>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-By: Peter De Schrijver <pdeschrijver@nvidia.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>