clk: sprd: fix compile-testing

I got a build failure with CONFIG_ARCH_SPRD=m when the
main portion of the clock driver failed to get linked into
the kernel:

ERROR: modpost: "sprd_pll_sc_gate_ops" [drivers/clk/sprd/sc9863a-clk.ko] undefined!
ERROR: modpost: "sprd_pll_ops" [drivers/clk/sprd/sc9863a-clk.ko] undefined!
ERROR: modpost: "sprd_div_ops" [drivers/clk/sprd/sc9863a-clk.ko] undefined!
ERROR: modpost: "sprd_comp_ops" [drivers/clk/sprd/sc9863a-clk.ko] undefined!
ERROR: modpost: "sprd_mux_ops" [drivers/clk/sprd/sc9863a-clk.ko] undefined!
ERROR: modpost: "sprd_gate_ops" [drivers/clk/sprd/sc9863a-clk.ko] undefined!
ERROR: modpost: "sprd_sc_gate_ops" [drivers/clk/sprd/sc9863a-clk.ko] undefined!
ERROR: modpost: "sprd_clk_probe" [drivers/clk/sprd/sc9863a-clk.ko] undefined!
ERROR: modpost: "sprd_clk_regmap_init" [drivers/clk/sprd/sc9863a-clk.ko] undefined!
ERROR: modpost: "sprd_pll_ops" [drivers/clk/sprd/sc9860-clk.ko] undefined!
ERROR: modpost: "sprd_div_ops" [drivers/clk/sprd/sc9860-clk.ko] undefined!
ERROR: modpost: "sprd_mux_ops" [drivers/clk/sprd/sc9860-clk.ko] undefined!

This is a combination of two trivial bugs:

- A platform should not be 'tristate', it should be a 'bool' symbol
  like the other platforms, if only for consistency, and to avoid
  surprises like this one.

- The clk Makefile does not traverse into the sprd subdirectory
  if the platform is disabled but the drivers are enabled for
  compile-testing.

Fixing either of the two would be sufficient to address the link failure,
but for correctness, both need to be changed.

Fixes: 2b1b799d76 ("arm64: change ARCH_SPRD Kconfig to tristate")
Fixes: d41f59fd92 ("clk: sprd: Add common infrastructure")
Acked-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm64/Kconfig.platforms

@@ -248,7 +248,7 @@ config ARCH_TEGRA
 	  This enables support for the NVIDIA Tegra SoC family.
 
 config ARCH_SPRD
-	tristate "Spreadtrum SoC platform"
+	bool "Spreadtrum SoC platform"
 	help
 	  Support for Spreadtrum ARM based SoCs
 

drivers/clk/Makefile

@@ -105,7 +105,7 @@ obj-$(CONFIG_CLK_SIFIVE)		+= sifive/
 obj-$(CONFIG_ARCH_SIRF)			+= sirf/
 obj-$(CONFIG_ARCH_SOCFPGA)		+= socfpga/
 obj-$(CONFIG_PLAT_SPEAR)		+= spear/
-obj-$(CONFIG_ARCH_SPRD)			+= sprd/
+obj-y					+= sprd/
 obj-$(CONFIG_ARCH_STI)			+= st/
 obj-$(CONFIG_ARCH_STRATIX10)		+= socfpga/
 obj-$(CONFIG_ARCH_SUNXI)		+= sunxi/