The variables SetupMode, AuditMode, DeployedMode are explicitly defined as
UINT8 in the UEFI specification. The type of SecureBoot is UINT8 in EDK2.

Use variable name secure_boot instead of sec_boot for the value of the
UEFI variable SecureBoot.

Avoid abbreviations in function descriptions.
Signed-off-by: NHeinrich Schuchardt <xypron.glpk@gmx.de>