Enable SecureBoot flag build on U540 and bootable on RISCV QEMU

[joshloo]

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This patch enables build with -DSECURE_BOOT_ENABLE=TRUE flag. However, some library included are null libraries here, and during boot, there's some unsupported function during SecureBootConfigDxe, specifically InvalidateInstructionCacheRange that needs to be fixed

Signed-off-by: Loo Tung Lun [email protected]

[bcran]

The TianoCore project doesn't use Pull Requests (yet), so you'll need to send the patch to [email protected] (see https://edk2.groups.io) to have it considered for inclusion.