T191: change PhysAddr, RAM, Frame, DevFrame and VNode_* cap types to have size in...

T191: change PhysAddr, RAM, Frame, DevFrame and VNode_* cap types to have size in bytes

This only changes the actual struct capability reprensentation for these
types.  Most of the code dealing with these types now uses log2ceil(bits) to
set the new `bytes` field.

Signed-off-by: Simon Gerber <simon.gerber@inf.ethz.ch>