parport: parport_pc: Introduce intel_bug_present function.

Put the code to check present of the Intel bug from parport_EPP_supported
into new intel_bug_present function. The later also return ECR register
to the state it has before function call.

Signed-off-by: Matwey V. Kornilov <matwey@sai.msu.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>