Explicitly bounds-check the id before accessing the opmode array. Seen
with GCC 13:

../drivers/regulator/max77802-regulator.c: In function 'max77802_enable':
../drivers/regulator/max77802-regulator.c:217:29: warning: array subscript [0, 41] is outside array bounds of 'unsigned int[42]' [-Warray-bounds=]
  217 |         if (max77802->opmode[id] == MAX77802_OFF_PWRREQ)
      |             ~~~~~~~~~~~~~~~~^~~~
../drivers/regulator/max77802-regulator.c:62:22: note: while referencing 'opmode'
   62 |         unsigned int opmode[MAX77802_REG_MAX];
      |                      ^~~~~~

Cc: Javier Martinez Canillas <javier@dowhile0.org>
Cc: Liam Girdwood <lgirdwood@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://lore.kernel.org/r/20230127225203.never.864-kees@kernel.orgSigned-off-by: Mark Brown <broonie@kernel.org>