clk/ti/adpll: Make const pointer error a static const array

Make const pointer error a static const array, removes a dereference
and shrinks object code a little.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://lore.kernel.org/r/20211127173036.150535-1-colin.i.king@gmail.com


Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>