platform/i2c: Move platform dependent code to the platform folder

Move all I2C platform dependent code from i2c_helper_linux.c to
platform/i2c.h and platform/i2c_linux.c.
Let the meson file handle i2c implementation selection depending on
the platform.

Change-Id: Ifc0a98cbffcebd35bddc47b3a9a4bae593f7dfd7
Signed-off-by: Antonio Vázquez Blanco <antoniovazquezblanco@gmail.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/91831
Reviewed-by: Peter Marheine <pmarheine@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Anastasia Klimchuk <aklm@chromium.org>
8 files changed