[PARISC] Reorganize sticore probe routine to be a little less convoluted

Fix some whitespace issues
Reorganise parisc_device probe routine to be a little less convoluted
Use ->hpa.start instead of ->hpa

Signed-off-by: Matthew Wilcox <willy@parisc-linux.org>

Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>