edk2: Update Maintainers.txt for packages moved to edk2-platforms

edk2: Update Maintainers.txt for packages moved to edk2-platforms

https://bugzilla.tianocore.org/show_bug.cgi?id=1467
https://bugzilla.tianocore.org/show_bug.cgi?id=1374
https://bugzilla.tianocore.org/show_bug.cgi?id=1793

Remove maintainers for ththe following packages that have been
imported to edk2-platforms/master
  * Omap35xxPkg
  * BeagleBoardPkg
  * QuarkSocPkg
  * QuarkPlatformPkg
  * Vlv2DeviceRefCodePkg
  * Vlv2TbltDevicePkg
  * OptionRomPkg

Cc: Zailiang Sun <zailiang.sun@intel.com>
Cc: Yi Qian <yi.qian@intel.com>
Cc: Kelly Steele <kelly.steele@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Michael Kubacki <michael.a.kubacki@intel.com>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
Reviewed-by: Ray Ni <ray.ni@intel.com>
Reviewed-by: Zailiang Sun <zailiang.sun@intel.com>
Reviewed-by: Kelly Steele <kelly.steele@intel.com>