refactor(memory sharing): helper functions

Refactor the memory sharing tests helper functions, to reuse
them in the test of subsequent patches.
Functions do not use hard-coded memory address and borrower in
the memory share operation. Instead, these are provided in the
arguments to the referred functions.

Change-Id: I1fda810e3acde23e33b5bbe06cbbbc0c652eed97
Signed-off-by: J-Alves <joao.alves@arm.com>
1 file changed