Add ARM11 MPCore CPU target support

gcc differentiates the mpcore-with-vfp from the mcpore-without-vfp
CPUs. The former is named just 'mpcore', while the latter is named
'mpcorenovfp'.

We only add one entry, 'mpcore' and let the user select whether or
not to use the VFP. We then name the CPU according to the user's
selection.

Signed-off-by: Sergi Granell <xerpi.g.12@gmail.com>
Tested-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>