drm/i915/icl: create function to identify combophy port

drm/i915/icl: create function to identify combophy port

This patch creates a function/wrapper to check if port is combophy port
instead of explicitly comparing ports.

Changes since V1:
 - keep all intel_port_is_* helper together (Lucas)

Signed-off-by: Mahesh Kumar <[email protected]>
Cc: Madhav Chauhan <[email protected]>
Cc: Manasi Navare <[email protected]>
Reviewed-by: Rodrigo Vivi <[email protected]>
Reviewed-by: Lucas De Marchi <[email protected]>
Signed-off-by: Rodrigo Vivi <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]