omap: Drop CONFIG_OMAP_VC_I2C_HS_MCODE

The symbol CONFIG_OMAP_VC_I2C_HS_MCODE always uses the default value.
Restructure the comment and code such that if a need arises later to use
another value we can address this then.

Signed-off-by: Tom Rini <trini@konsulko.com>