target/arm: Add "ARM_CP_NO_GDB" as a new bit field for ARMCPRegInfo type

target/arm: Add "ARM_CP_NO_GDB" as a new bit field for ARMCPRegInfo type

This is a preparation for the coming feature of creating dynamically an XML
description for the ARM sysregs.
A register has ARM_CP_NO_GDB enabled will not be shown in the dynamic XML.
This bit is enabled automatically when creating CP_ANY wildcard aliases.
This bit could be enabled manually for any register we want to remove from the
dynamic XML description.

Signed-off-by: Abdallah Bouassida <abdallah.bouassida@lauterbach.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 1524153386-3550-2-git-send-email-abdallah.bouassida@lauterbach.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>