fix(el3-runtime): typecast operands to match data type

This corrects the MISRA violation C2012-10.3:
The value of an expression shall not be assigned to an object with a
narrower essential type or of a different essential type category.
Replaced usage of 'unsigned int' with 'size_t' to ensure type
consistency and prevent assignment to a narrower or different
essential type.

Change-Id: I79501e216a04753ebd005d64375357b9332440d9
Signed-off-by: Nithin G <nithing@amd.com>
Signed-off-by: Maheedhar Bollapalli <maheedharsai.bollapalli@amd.com>
10 files changed