atom-pc: remove kernel video mode parameters

atom-pc: remove kernel video mode parameters

The kernel video mode parameters are not needed with the atom-pc linux-wrs
configuration. Without them, we boot up with a standard 80x25 text display
until the Intel i915 driver is initialized, at which point we switch to a
higher resolution text mode. Afterwards, a sato image will start the splash
screen and successfully boot to X.

Tested on the Toshiba NB305 netbook and the Black Sand development board.

[BUGID #450]

Signed-off-by: Darren Hart <dvhart@linux.intel.com>
CC: Tom Zanussi <tom.zanussi@intel.com>
CC: Bruce Ashfield <bruce.ashfield@windriver.com>
CC: Richard Purdie <rpurdie@linux.intel.com>