Update relevant "msr {s,c}prs, reg" instructions

Updates relevant "msr {s,c}prs, reg" instructions to
"msr {s,c}prs_fsxc, reg" to avoid loosing bits when
setting SPSR/CPSR.

Reviewed-by: Joakim Bech <joakim.bech@linaro.org>
Reviewed-by: Pascal Brand <pascal.brand@linaro.org>
plat-vexpress: Set CPSR.A when initializing

Sets CPSR.A when initializing a core. The bit should already be
set by the OP-TEE Dispatcher in ARM Trusted Firmware but in case
it isn't make sure the bit is set.

Reviewed-by: Joakim Bech <joakim.bech@linaro.org>
Reviewed-by: Pascal Brand <pascal.brand@linaro.org>
Tested-by: Pascal Brand <pascal.brand@linaro.org> (STM platform)
Tested-by: Jens Wiklander <jens.wiklander@linaro.org> (FVP platform)
Fix wrong parameter in GCM authentication

Signed-off-by: Pascal Brand <pascal.brand@st.com>
Reviewed-by: Jerome Forissier <jerome.forissier@linaro.org>
Tested-by: Pascal Brand <pascal.brand@linaro.org> (STM platform)
Travis now runs checkpatch.pl

Note that this implies:
- If checkpatch.pl fails, Travis results is now "failed". In such a case,
  it must be checked that
  - checkpatch.pl fails for good reason (GP CamelCase style for ex.)
  - all the compilations steps are fine
- Signing the commit is now mandatory
     git commit -s ...
- When pushing several commits on the same branch (same pull-request),
  checkpatch.pl is run only on the code differences given by the
  the last commit

Reviewed-by: Jerome Forissier <jerome.forissier@linaro.org>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>
Tested-by: Pascal Brand <pascal.brand@linaro.org>
Signed-off-by: Pascal Brand <pascal.brand@st.com>