Add CAN->filter to API and add placeholders to hal's

Add filter function and modify CAN->read definition to allow reading specific messages.
Add bitfields definition to LPC11XX target

Generated from UM10398
Add can_api hal implementation to LPC11CXX target

Most of the functionality works, interrupts might need a little more work.
Merge pull request #91 from jorisa/master

Add CAN api filter support and LPC11CXX CAN implementation