REAL(8) --> REAL(KIND=dp) in ipi_driver.F

Hopefully this will be OK with all compiler -- and it is more 
consistent with CP2K style anyway.



git-svn-id: svn://svn.code.sf.net/p/cp2k/code/trunk@14079 bac0169d-1eea-4375-b5f6-f89d2ced9994