interfaces: can: use largest buffer available buffer
interfaces: can: use largest buffer available buffer

Use the new csp_buffer_size() function instead of hardcoded value.

Signed-off-by: Jeppe Ledet-Pedersen <04ca46c996f3ce83ad557eea1980ca8ca065ba1b@satlab.org>

satlab/libcsp,pacheco017/libcsp,marshall/libcsp,GomSpace/libcsp,GomSpace/libcsp,Psykar/kubos,satlab/libcsp,marshall/libcsp,libcsp/libcsp,pacheco017/libcsp,kubostech/KubOS,pacheco017/libcsp,Psykar/kubos,Psykar/kubos,satlab/libcsp,Psykar/kubos,Psykar/kubos,pacheco017/libcsp,GomSpace/libcsp,marshall/libcsp,Psykar/kubos,libcsp/libcsp,Psykar/kubos,kubostech/KubOS