Add GetSystemPropertyUint32Base

Yes I assumed the int could be written as hexa in properties.
Yes I merged a change adding an hexa property
Yes I broke multiples devices
ヾ(_ _。）

Breakage was happening when you set these properties using hexa num
  bluetooth.l2cap.le.credit_default.value
  bluetooth.l2cap.le.credit_threshold.value

Bug: 263323082
Test: atest net_test_osi
Change-Id: Ie58c1bc0d637fc0fabd9797813187d1897c0df51