StandaloneMmPkg: Fix ECC error 1001 in SMM Memory pool management

StandaloneMmPkg: Fix ECC error 1001 in SMM Memory pool management

Bugzilla: 3150 (https://bugzilla.tianocore.org/show_bug.cgi?id=3150)

Fix the following error reported by the Ecc tool:
[1001] 'TAB' character is not allowed in source code, please
replace each 'TAB' with two spaces.

Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
Acked-by: Jiewen Yao <Jiewen.yao@intel.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>