[i.MX6][CPLD][driver/seco] Add driver v1.0 for SECO CPLD LPC/GPIO

This driver coming from SECO driver library:
- driver: seco_cpld_imx6
- version: v1.0

This driver is generic but is used only by [i.MX6][928].
The WEIM bus is used to communicate with the CPLD.
There are two CPLD's versions:
- LPC bridge: a LPC bridge is implemented and the actual drivers
  compatible with this bus are:
	- sio_xr28v382: support for MaxLinear XR28V382 with x2 UARTs
	- sio_w83627: support for Nuvoton W83627 superIO
- GPIO x8 + PWM: a GPIO expander plus a PWM controller are present into
  CPLD. In this case the driver are cgpio_expander.c and pwm_cpld.c
  respectively.
The serial_core of the kernel has been modified inorder to support the
specific UART type coming from LPC compatible driver.
Since, as mentioned, this driver is used only by the [928] module,
please, refer to its dts file about the device-tree, where there is the
hierarchy:

WEIM
 |__ CPLD
     |__ GPIO + PWM
     |__ LPC
          |__ XR28V382
          |__ W83627

Note: all node on the same level are mutually exclusive