ARM: dts: AM33XX: mcasp: Add location for data port registers to reg-property

This patch adds a second tuple to reg property. The new property tuple
describes the memory location for data port registers mapped trough
L3 bus on am33xx. The both property tuples are named accordingly in
the reg-names property.

Signed-off-by: Hebbar, Gururaja <gururaja.hebbar@ti.com>
Signed-off-by: Darren Etheridge <detheridge@ti.com>
Signed-off-by: Jyri Sarha <jsarha@ti.com>
Signed-off-by: Benoit Cousson <bcousson@baylibre.com>