EmbeddedPkg/PrePiHobLib: Fix SetBootMode return value #485

Job	Run time
Analyze (ArmPkg, IA32,X64)	3m 30s
Analyze (CryptoPkg, IA32)	22m 3s
Analyze (CryptoPkg, X64)	22m 43s
Analyze (DynamicTablesPkg, IA32,X64)	13m 34s
Analyze (FatPkg, IA32,X64)	12m 45s
Analyze (FmpDevicePkg, IA32,X64)	11m 16s
Analyze (IntelFsp2Pkg, IA32,X64)	11m 37s
Analyze (IntelFsp2WrapperPkg, IA32,X64)	8m 45s
Analyze (MdeModulePkg, IA32)	19m 43s
Analyze (MdeModulePkg, X64)	17m 36s
Analyze (MdePkg, IA32,X64)	13m 21s
Analyze (PcAtChipsetPkg, IA32,X64)	11m 39s
Analyze (PrmPkg, IA32,X64)	11m 38s
Analyze (SecurityPkg, IA32,X64)	13m 22s
Analyze (ShellPkg, IA32,X64)	11m 51s
Analyze (SourceLevelDebugPkg, IA32,X64)	13m 29s
Analyze (StandaloneMmPkg, IA32,X64)	10m 15s
Analyze (UefiCpuPkg, IA32,X64)	17m 16s
Analyze (UnitTestFrameworkPkg, IA32,X64)	12m 58s
	4h 19m 21s

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