Bluetooth: Controller: Fix regression in overlapping 1M and Coded Scan

Fix regression in overlapping 1M and Coded PHY scan window
by considering rounding margins when checking for same
interval and same window durations.

Relates to commit c14bde45 ("Bluetooth: Controller: Fix
overlapping 1M and Coded PHY scannning").

Signed-off-by: Vinayak Kariappa Chettimada <vich@nordicsemi.no>