build: rename CONFIG_QGA_NTDDDISK to CONFIG_QGA_NTDDSCSI

build: rename CONFIG_QGA_NTDDDISK to CONFIG_QGA_NTDDSCSI

There was inconsistency between commits:

  50cbebb9a3 configure: add configure check for ntdddisk.h
  a3ef3b2272 qga: added bus type and disk location path

The first commit added #define CONFIG_QGA_NTDDDISK but the second commit
expected the name to be CONFIG_QGA_NTDDSCSI. As a result the code in
second patch was never used.

Renaming the option to CONFIG_QGA_NTDDSCSI to match the name of header
file that is being checked for.

Signed-off-by: Tomáš Golembiovský <tgolembi@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Sameeh Jubran <sjubran@redhat.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>