media: atomisp: don't set hpll_freq twice with different values
The logic which sets the hpll_freq for BYT sets hpll_freq
to 1600MHz, but ignores it, and sets it again after reading
from-device-specific EFI vars (this time, using a default
of 2000MHz).
Remove the first set, as this will be overriden anyway.
While here, do minor adjustments on comments and on a
printk message.