Maintainers.txt: Add Liran and Nikita as OvmfPkg/PvScsiDxe reviewers

Maintainers.txt: Add Liran and Nikita as OvmfPkg/PvScsiDxe reviewers

Laszlo suggested that as I have contributed the OvmfPkg PVSCSI driver, I
will also register myself as a reviewer in Maintainers.txt.

In addition, as Nikita have assisted the development of the PVSCSI
driver and have developed another similar OvmfPkg SCSI driver, add him
as a reviewer to PVSCSI driver as-well.

Cc: Nikita Leshenko <nikita.leshchenko@oracle.com>
Suggested-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Message-Id: <20200331110244.51409-1-liran.alon@oracle.com>
Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com>
[lersek@redhat.com: fixup "F:" pattern by appending slash character]
Reviewed-by: Laszlo Ersek <lersek@redhat.com>