sunxi: sun8i_a83t: make more clock functions SPL only

In clock_sun8i_a83t.c, responsible for (mostly early) clock setup on the
Allwinner A83T SoC, many functions are only needed by the SPL, and are
thus already guarded by CONFIG_SPL_BUILD.

Over the years drivers like for the UART or I2C were converted to DM,
so they care about clock setup themselves now, by using a proper DM clock
driver.

This means those devices need the clock setup functions here for the SPL
only. Include those functions into the existing CONFIG_SPL_BUILD guards,
so they are compiled for the SPL only.

This avoids unnecessary code in U-Boot proper and helps further
refactoring. Add some comments on the way to help understanding of the
file.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>

arch/arm/mach-sunxi/clock_sun8i_a83t.c

@@ -46,7 +46,6 @@ void clock_init_safe(void)
 	/* timestamp */
 	writel(1, 0x01720000);
 }
-#endif
 
 void clock_init_uart(void)
 {
@@ -70,7 +69,6 @@ void clock_init_uart(void)
 			   CONFIG_CONS_INDEX - 1));
 }
 
-#ifdef CONFIG_SPL_BUILD
 void clock_set_pll1(unsigned int clk)
 {
 	struct sunxi_ccm_reg * const ccm =
@@ -102,8 +100,9 @@ void clock_set_pll1(unsigned int clk)
 		CPU_CLK_SRC_PLL1 << C1_CPUX_CLK_SRC_SHIFT,
 	       &ccm->cpu_axi_cfg);
 }
-#endif
+#endif /* CONFIG_SPL_BUILD */
 
+/* DRAM and PLL_PERIPH0 clock (used by the MMC driver) */
 void clock_set_pll5(unsigned int clk)
 {
 	struct sunxi_ccm_reg * const ccm =