tty: atmel_serial: Use devm_platform_ioremap_resource()

Simplify the request port function by using a single call
to devm_platform_ioremap_resource().

This will also enhance the printing from /proc/iomem:

cat /proc/iomem | grep flexcom ; cat /proc/iomem | grep serial

f0004000-f00041ff : f0004000.flexcom flexcom@f0004000
f8020000-f80201ff : f8020000.flexcom flexcom@f8020000
f0004200-f00043ff : f0004200.serial serial@200
f8020200-f80203ff : f8020200.serial serial@200
fffff200-fffff3ff : fffff200.serial serial@fffff200

Signed-off-by: Mihai Sain <mihai.sain@microchip.com>
Tested-by: Andrei Simion <andrei.simion@microchip.com>
Reviewed-by: Hari Prasath Gujulan Elango <hari.prasathge@microchip.com>
Link: https://lore.kernel.org/r/20241105131946.22449-1-mihai.sain@microchip.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>