ArmPlatformPkg/Bds: Getting and editing IP addresses

Reworked GetHIInputIP() function to use "NetLibStrToIp4()" library
function to parse the IPv4 address instead of doing it by itself.

Added function EditHIInputIP() in BdsHelper.c to edit an IPv4 address.
To be used when updating a tftp boot option.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ronald Cron <ronald.cron@arm.com>
Reviewed-By: Olivier Martin <olivier.martin@arm.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15660 6f19259b-4bc3-4df7-8a09-765794883524