sunxi: Fix old GMAC pinmux setup

Commit 5bc4cd0 ("sunxi: move non-essential code out of s_init()")
moved the call to eth_init_board() from s_init() into board_init_f().
This means it's now only called from the SPL, which makes sense for
most of the other moved low-level functions. However the GMAC pinmux and
clock setup in eth_init_board() was not happy about that, so it broke
the sun7i GMAC.

Since Ethernet is of no use in the SPL anyway, just move the call into
board_init(), which is only run in U-Boot proper.

This fixes Ethernet operation for the A20 SoCs, which broke in
v2022.04-rc1, with the above mentioned commit.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Tested-by: Petr Štetiar <ynezz@true.cz> [a20-olinuxino-lime2]

arch/arm/mach-sunxi/board.c

@@ -333,7 +333,6 @@ void board_init_f(ulong dummy)
 	clock_init();
 	timer_init();
 	gpio_init();
-	eth_init_board();
 
 	spl_init();
 	preloader_console_init();

board/sunxi/board.c

@@ -30,6 +30,7 @@
 #include <asm/arch/prcm.h>
 #include <asm/arch/pmic_bus.h>
 #include <asm/arch/spl.h>
+#include <asm/arch/sys_proto.h>
 #include <asm/global_data.h>
 #include <linux/delay.h>
 #include <u-boot/crc.h>
@@ -308,6 +309,8 @@ int board_init(void)
 #endif
 #endif	/* CONFIG_DM_MMC */
 
+	eth_init_board();
+
 	return 0;
 }