Fix OpenSSF-related warnings for GCC

These warnings were not flagged by Clang but triggered by the GCC compiler.

GCC 9.4 throws relocation errors when linking with -pie unless all objects are compiled with -fpie.
To resolve this, replaced -pie with -fpie to ensure consistent position-independent code generation
during both compilation and linking.

Change-Id: Iba7ce1d0e84d8040dafe65c41fd553c342507cbc
Signed-off-by: Yuvaraj Venkatesh <yuvaraj.venkatesh@arm.com>