EmbeddedPkg: Fix build error for MmcDxe

EmbeddedPkg: Fix build error for MmcDxe

The following command line:
build -b NOOPT -a IA32 -t VS2017 -p edk2\EmbeddedPkg\EmbeddedPkg.dsc

Generates the following error:
MmcDxe.lib(Diagnostics.obj) : error LNK2001:
unresolved external symbol __allshl
MmcDxe.lib(Diagnostics.obj) : error LNK2001:
unresolved external symbol __aullshr
MmcDxe.lib(MmcBlockIo.obj) : error LNK2001:
unresolved external symbol __allmul

These erros are due to the use of shift/multiply operations
on UINT64 variable on a IA32 architecture.

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
Reviewed-by: Leif Lindholm <leif@nuviainc.com>