clk: meson: mpll: add init callback and regs

Until now (gx and axg), the mpll setting on boot (whatever the
bootloader) was good enough to generate a clean fractional division.

It is not the case on the g12a. While moving away from the vendor u-boot,
it was noticed the fractional part of the divider was no longer applied.
Like on the pll, some magic settings need to applied on the mpll
register.

This change adds the ability to do that on the mpll driver.

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>

drivers/clk/meson/clk-mpll.h

@@ -18,6 +18,8 @@ struct meson_clk_mpll_data {
 	struct parm n2;
 	struct parm ssen;
 	struct parm misc;
+	const struct reg_sequence *init_regs;
+	unsigned int init_count;
 	spinlock_t *lock;
 	u8 flags;
 };