e-hal: Update to match new PL eLink interface.

* src/e-hal/src/epiphany-hal-data.h: Update to match new PL eLink
interface.
* src/e-hal/src/epiphany-hal.c (int e_reset_system):
Likewise.
e-hal: Temporarily limit writes to 4byte chunks

* src/e-hal/src/epiphany-hal.c (ssize_t ee_write_buf): Temporarily
limit writes to 4 byte chunks to work around temporary limitations
new eLink programmable logic.