mfd: kempld-core: Fix 'assignment of read-only location' error

 drivers/mfd/kempld-core.c: In function 'kempld_register_cells_generic':
 drivers/mfd/kempld-core.c:105:13: error: assignment of read-only location 'devs[i++]'
  105 |   devs[i++] = kempld_devs[KEMPLD_I2C];
      |             ^
 drivers/mfd/kempld-core.c:108:13: error: assignment of read-only location 'devs[i++]'
  108 |   devs[i++] = kempld_devs[KEMPLD_WDT];
      |             ^
 drivers/mfd/kempld-core.c:111:13: error: assignment of read-only location 'devs[i++]'
  111 |   devs[i++] = kempld_devs[KEMPLD_GPIO];
      |             ^
 drivers/mfd/kempld-core.c:114:13: error: assignment of read-only location 'devs[i++]'
  114 |   devs[i++] = kempld_devs[KEMPLD_UART];
      |             ^

Fixes: e49aa9a9bd22 ("mfd: core: Make a best effort attempt to match devices with the correct of_nodes")
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Lee Jones <lee.jones@linaro.org>