arm64: dts: ti: Drop reg-io-width/reg-shift from UART nodes

8250_omap compatible UART IPs on all SoCs have registers aligned at 4
byte address boundary and constant byte addressability. Thus there is no
need for reg-io-width or reg-shift DT properties.  These properties are
not used by 8250_omap driver nor documented as part of binding document.
Therefore drop them.

This is in preparation to move omap-serial.txt to YAML format.

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Link: https://lore.kernel.org/r/20210607134558.23704-1-vigneshr@ti.com