lib: heap: Added checks for integer overflow
lib: heap: Added checks for integer overflow

check the integer overflow while allocating the memory from heap.

CRs-Fixed: 692478
Change-Id: I73e8ffe74efc7aa580af43142bdf733bb2d8610a

Foxda-Tech/polaris-bootable-bootloader-lk,Foxda-Tech/polaris-bootable-bootloader-lk,efidroid/lk,CanarySolutions/little-kernel,efidroid/lk,CanarySolutions/little-kernel,Foxda-Tech/polaris-bootable-bootloader-lk,Foxda-Tech/polaris-bootable-bootloader-lk,efidroid/lk,CanarySolutions/little-kernel,efidroid/lk,CanarySolutions/little-kernel,CanarySolutions/little-kernel,Foxda-Tech/polaris-bootable-bootloader-lk,efidroid/lk