clk: imx: add i.MX93 clk gate

i.MX93 LPCG is different from i.MX8M CCGR. Although imx_clk_hw_gate4_flags
is used here, it not strictly match i.MX93. i.MX93 has such design:
- LPCG_DIRECT use BIT0 as on/off gate when LPCG_AUTHEN CPU_LPM is 0
- LPCG_LPM_CUR use BIT[2:0] as on/off gate when LPCG_AUTHEN CPU_LPM is 1

The current implementation suppose CPU_LPM is 0, and use LPCG_DIRECT
BIT[1:0] as on/off gate. Although BIT1 is touched, actually BIT1 is
reserved.

And imx_clk_hw_gate4_flags use mask 0x3 to determine whether the clk
is enabled or not, but i.MX93 LPCG only use BIT0 to control when CPU_LPM
is 0. So clk disabled unused during kernel boot not able to gate off
the unused clocks.

To match i.MX93 LPCG, introduce imx93_clk_gate.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Ye Li <ye.li@nxp.com>
Reviewed-by: Jacky Bai <ping.bai@nxp.com>
Reviewed-by: Abel Vesa <abel.vesa@linaro.org>
Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
Link: https://lore.kernel.org/r/20220830033137.4149542-6-peng.fan@oss.nxp.com