ARM: 9269/1: vfp: Add hwcap for FEAT_DotProd

Advanced Dot product is a feature present in AArch32 state for Armv8 and
is represented by ISAR6 identification register.

This feature denotes the presence of UDOT and SDOT instructions and hence adding a hwcap will enable the userspace to check it before trying to use those instructions.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>