cmd/Kconfig: CONFIG_CMD_CLK should depend on CONFIG_CLK

cmd/Kconfig: CONFIG_CMD_CLK should depend on CONFIG_CLK

The clk command cannot provide useful output without a clock driver.
So let it depend on CONFIG_CLK.

Since commit 258c1002383e ("cmd: clk: Use dump function from clk_ops")
the remark about deprecation is obsolete. Remove it.

Since commit 7ab418fbe612 ("clk: add support for setting clk rate from
cmdline") the clk command can be used to set clock frequencies. Mention
it.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>