pmdomain: imx: Make IMX8M/IMX9 BLK_CTRL tristate

Convert IMX8M_BLK_CTRL and IMX9_BLK_CTRL from bool to tristate
to allow building as loadable modules.

This change is required to support Android devices using Generic Kernel
Image (GKI) kernels, where SoC-specific drivers must be built as loadable
modules rather than built into the core kernel image.

For i.MX8M and i.MX9 devices running Android with GKI kernels, the
BLK_CTRL drivers therefore need to be loadable. Without tristate
support, power domains cannot be initialized correctly, making these
systems non-functional under GKI.

Add prompt strings to make these options visible and configurable
in menuconfig, keeping them enabled by default on appropriate platforms.

Also remove the IMX_GPCV2_PM_DOMAINS dependency from IMX9_BLK_CTRL.
This dependency was incorrect from the beginning because i.MX93 uses a
different power domain architecture compared to i.MX8M series:

- i.MX8M uses GPCv2 (General Power Controller v2) for power domain
  management, hence IMX8M_BLK_CTRL correctly depends on it.

- i.MX93 uses BLK_CTRL directly without GPCv2. The hardware doesn't
  have GPCv2 at all.

Signed-off-by: Zhipeng Wang <zhipeng.wang_1@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Ulf Hansson <ulfh@kernel.org>

drivers/pmdomain/imx/Kconfig

@@ -10,15 +10,18 @@ config IMX_GPCV2_PM_DOMAINS
 	default y if SOC_IMX7D
 
 config IMX8M_BLK_CTRL
-	bool
-	default SOC_IMX8M && IMX_GPCV2_PM_DOMAINS
+	tristate "i.MX8M BLK CTRL driver"
+	depends on SOC_IMX8M
+	depends on IMX_GPCV2_PM_DOMAINS
 	depends on PM_GENERIC_DOMAINS
 	depends on COMMON_CLK
+	default y
 
 config IMX9_BLK_CTRL
-	bool
-	default SOC_IMX9 && IMX_GPCV2_PM_DOMAINS
+	tristate "i.MX93 BLK CTRL driver"
+	depends on SOC_IMX9
 	depends on PM_GENERIC_DOMAINS
+	default y
 
 config IMX_SCU_PD
 	bool "IMX SCU Power Domain driver"