oem-ibm: Adding BIOS attribute for dynamic deallocation of Memory

This commit adds BIOS attribute for allowing user to enable/disable
the dynamic deallocation of memory.

Tested: Verified the BIOS attribute with get bios attribute command from
pldmtool.

Change-Id: Ife96c4544adf142e6c354e0dbd658d96625b8c13
Signed-off-by: Riya Dixit <riyadixitagra@gmail.com>