Core: Fix secure gateway function clone issue in GNUARM

A known issues is that secure gateway functions with attribute
cmse_nonsecure_entry may be cloned by GNUARM in build. The function
symbol genreted in clone may break the link.

This issue can be fixed by adding attribute noclone to secure
gateway functions in GNUARM. Since Armclang doesn't support noclone
attritbue, the current workaround is to add attribute noinline to
some secure gateway functions, instead of noclone, to achieve the
same effect.

This patch improves the workaround.
- Add attribute noclone to secure gatewary functions in GNUARM
- Remove noinline attribute in other compilers
- Apply this workaround to all secure gatewary functions

Change-Id: Ia29595f6f3b663f928c9507f1d744dae2377a357
Signed-off-by: David Hu <david.hu@arm.com>