Move all command code into its own directory

There are a lot of unrelated files in common, including all of the commands.
Moving them into their own directory makes them easier to find and is more
logical.

Some commands include non-command code, such as cmd_scsi.c. This should be
sorted out at some point so that the function can be enabled with or without
the associated command.

Unfortunately, with m68k I get this error:

m68k:  +   M5329AFEE
+arch/m68k/cpu/mcf532x/start.o: In function `_start':
+arch/m68k/cpu/mcf532x/start.S:159:(.text+0x452): relocation truncated to fit: R_68K_PC16 against symbol `board_init_f' defined in .text.board_init_f section in common/built-in.o

I hope someone can shed some light on what this means. I hope it isn't
depending on the position of code in the image.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
Acked-by: Stefan Roese <sr@denx.de>
Acked-by: Przemyslaw Marczak <p.marczak@samsung.com>

cmd/cmd_misc.c

@@ -0,0 +1,67 @@
+/*
+ * (C) Copyright 2001
+ * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+/*
+ * Misc functions
+ */
+#include <common.h>
+#include <command.h>
+#include <console.h>
+
+static int do_sleep(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	ulong start = get_timer(0);
+	ulong delay;
+
+	if (argc != 2)
+		return CMD_RET_USAGE;
+
+	delay = simple_strtoul(argv[1], NULL, 10) * CONFIG_SYS_HZ;
+
+	while (get_timer(start) < delay) {
+		if (ctrlc())
+			return (-1);
+
+		udelay(100);
+	}
+
+	return 0;
+}
+
+U_BOOT_CMD(
+	sleep ,    2,    1,     do_sleep,
+	"delay execution for some time",
+	"N\n"
+	"    - delay execution for N seconds (N is _decimal_ !!!)"
+);
+
+#ifdef CONFIG_CMD_TIMER
+static int do_timer(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	static ulong start;
+
+	if (argc != 2)
+		return CMD_RET_USAGE;
+
+	if (!strcmp(argv[1], "start"))
+		start = get_timer(0);
+
+	if (!strcmp(argv[1], "get")) {
+		ulong msecs = get_timer(start) * 1000 / CONFIG_SYS_HZ;
+		printf("%ld.%03d\n", msecs / 1000, (int)(msecs % 1000));
+	}
+
+	return 0;
+}
+
+U_BOOT_CMD(
+	timer,    2,    1,     do_timer,
+	"access the system timer",
+	"start - Reset the timer reference.\n"
+	"timer get   - Print the time since 'start'."
+);
+#endif