MdeModulePkg/UefiBootManagerLib: fix LoadImage/StartImage status code rep.

MdeModulePkg/UefiBootManagerLib: fix LoadImage/StartImage status code rep.

In the EFI_RETURN_STATUS_EXTENDED_DATA structure from PI-1.7, there may be
padding between the DataHeader and ReturnStatus members. The
REPORT_STATUS_CODE_EX() macro starts populating the structure immediately
after DataHeader, therefore the source data must provide for the padding.

Extract the BmReportLoadFailure() function from EfiBootManagerBoot(),
prepare a zero padding (if any) in a temporary
EFI_RETURN_STATUS_EXTENDED_DATA object, and fix the
REPORT_STATUS_CODE_EX() macro invocation.

Cc: Dandan Bi <dandan.bi@intel.com>
Cc: Hao Wu <hao.a.wu@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Sean Brogan <sean.brogan@microsoft.com>
Cc: Star Zeng <star.zeng@intel.com>
Bugzilla: https://bugzilla.tianocore.org/show_bug.cgi?id=1539
Fixes: c2cf8720a5aad74230767a1f11bade2d86de3745
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ray Ni <ray.ni@intel.com>