clapack: Disable for MIPS platforms

Disable this package for MIPS because it needs IRIX headers and
libraries.

Fixes:
   http://autobuild.buildroot.net/results/370/370f964441722675820c644403dde7fbc683a315/



Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Reviewed-by: Markos Chandras <Markos.Chandras@imgtec.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>