misc: xilinx_sdfec: Add stats & status ioctls

SD-FEC statistic data are:
- count of data interface errors (isr_err_count)
- count of Correctable ECC errors (cecc_count)
- count of Uncorrectable ECC errors (uecc_count)

Add support:
1. clear stats ioctl callback which clears collected
statistic data,
2. get stats ioctl callback which reads a collected
statistic data,
3. set default configuration ioctl callback,
4. start ioctl callback enables SD-FEC HW,
5. stop ioctl callback disables SD-FEC HW.

In a failed state driver enables the following ioctls:
- get status
- get statistics
- clear stats
- set default SD-FEC device configuration

Tested-by: Santhosh Dyavanapally <SDYAVANA@xilinx.com>
Tested by: Punnaiah Choudary Kalluri <punnaia@xilinx.com>
Tested-by: Derek Kiernan <derek.kiernan@xilinx.com>
Tested-by: Dragan Cvetic <dragan.cvetic@xilinx.com>
Signed-off-by: Derek Kiernan <derek.kiernan@xilinx.com>
Signed-off-by: Dragan Cvetic <dragan.cvetic@xilinx.com>
Link: https://lore.kernel.org/r/1564216438-322406-7-git-send-email-dragan.cvetic@xilinx.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>