[MMSYS]: Improve AddSoundProfile, by Victor Martinez Calvo (with 1 minor modification...

[MMSYS]: Improve AddSoundProfile, by Victor Martinez Calvo (with 1 minor modification by myself):
◾ Don't return TRUE when CB_SETITEMDATA fails.
◾ Avoid pScheme NULL dereference if allocation fails. CID 1223154
◾ Avoid overflowing the destiny buffer by using StringCchCopy() CID 510953
and:
1) Make it more readable by returning as soon as possible when an error happens.
2) Make it more readable by reducing the nested ifs-checks.
3) Remove the added string in the combobox if the sound scheme buffer mem allocation fails (pt.3 modified).
CORE-11603 #resolve #comment Thanks!

svn path=/trunk/; revision=72000