clk: pistachio: Fix initconst confusion

A variable pointing to const isn't const itself. It has to contain
"const" keyword after "*" too. So to keep it in __initconst (and not
mark properly as __initdata), add the "const" keyword exactly there.

Note we need to update struct pistachio_mux too. On the other hand, the
clk core already counts with "const char *const" already.

[js] more explanatory commit message.

Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: linux-clk@vger.kernel.org
Cc: Martin Liska <mliska@suse.cz>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220920055838.22637-1-jslaby@suse.cz


Signed-off-by: Stephen Boyd <sboyd@kernel.org>