i2c: wmt: add platform type VIAI2C_PLAT_WMT

Enumeration variables are added to differentiate
between different platforms.

Acked-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Hans Hu <hanshu-oc@zhaoxin.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>

i2c: wmt: rename something

1. The I2C IP for both wmt and zhaoxin originates from VIA. Rename
common registers, functions, and variable names to follow the
VIAI2C_ and viai2c_ naming conventions for consistency and clarity.
2. rename i2c_dev to i2c, to shorten the length of a line.
3. rename wait_result to time_left, make it better to reflect the meaning
of the value returned by wait_for_completion_timeout().
4. remove TCR_MASTER_WRITE, its value is 0.

Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Hans Hu <hanshu-oc@zhaoxin.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>

i2c: wmt: split out common files

Since the I2C IP of both wmt and zhaoxin originates from VIA,
it is better to separate the common code first.
The common driver is named as i2c-viai2c-common.c.
Old i2c-wmt.c renamed to i2c-viai2c-wmt.c.

The MAINTAINERS file will be updated accordingly in upcoming commits.

Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Hans Hu <hanshu-oc@zhaoxin.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>