regulator: mp5416: Constify struct regulator_desc

'struct regulator_desc' is not modified in this driver.

Constifying this structure moves some data to a read-only section, so
increase overall security, especially when the structure holds some
function pointers.

On a x86_64, with allmodconfig:
Before:
======
   text	   data	    bss	    dec	    hex	filename
   3516	   5320	     32	   8868	   22a4	drivers/regulator/mp5416.o

After:
=====
   text	   data	    bss	    dec	    hex	filename
   8508	    320	     32	   8860	   229c	drivers/regulator/mp5416.o

--
Compile tested only
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://patch.msgid.link/fd8d1307f211ec7754f46b6678c04309556003bc.1725807320.git.christophe.jaillet@wanadoo.frSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/mp5416.c

@@ -163,7 +163,7 @@ static const struct regulator_ops mp5416_buck_ops = {
 	.set_ramp_delay		= regulator_set_ramp_delay_regmap,
 };
 
-static struct regulator_desc mp5416_regulators_desc[MP5416_MAX_REGULATORS] = {
+static const struct regulator_desc mp5416_regulators_desc[MP5416_MAX_REGULATORS] = {
 	MP5416BUCK("buck1", 1, mp5416_I_limits1, MP5416_REG_CTL1, BIT(0), 1),
 	MP5416BUCK("buck2", 2, mp5416_I_limits2, MP5416_REG_CTL1, BIT(1), 2),
 	MP5416BUCK("buck3", 3, mp5416_I_limits1, MP5416_REG_CTL1, BIT(2), 1),
@@ -174,7 +174,7 @@ static struct regulator_desc mp5416_regulators_desc[MP5416_MAX_REGULATORS] = {
 	MP5416LDO("ldo4", 4, BIT(1)),
 };
 
-static struct regulator_desc mp5496_regulators_desc[MP5416_MAX_REGULATORS] = {
+static const struct regulator_desc mp5496_regulators_desc[MP5416_MAX_REGULATORS] = {
 	MP5416BUCK("buck1", 1, mp5416_I_limits1, MP5416_REG_CTL1, BIT(0), 1),
 	MP5416BUCK("buck2", 2, mp5416_I_limits2, MP5416_REG_CTL1, BIT(1), 1),
 	MP5416BUCK("buck3", 3, mp5416_I_limits1, MP5416_REG_CTL1, BIT(2), 1),