pmdomain: amlogic: Constify struct meson_secure_pwrc_domain_data

'struct meson_secure_pwrc_domain_data' are not modified in these drivers.

Constifying these structures moves some data to a read-only section, so
increases overall security.

On a x86_64, with allmodconfig:
Before:
======
   text	   data	    bss	    dec	    hex	filename
   9248	    408	      0	   9656	   25b8	drivers/pmdomain/amlogic/meson-secure-pwrc.o

After:
=====
   text	   data	    bss	    dec	    hex	filename
   9344	    304	      0	   9648	   25b0	drivers/pmdomain/amlogic/meson-secure-pwrc.o

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/e71abd8d75dd842690e5a11e38037bcf5feac189.1751816732.git.christophe.jaillet@wanadoo.fr


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>