Staging: vme: declare vme_calc_slot() as static

vme_calc_slot() is not used anywhere other than vme.c so it should be
declared as static.

Signed-off-by: Bill Pemberton <wfp5p@virginia.edu>
Cc: Martyn Welch <martyn.welch@ge.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>