ia64: doc: tweak whitespace for 'console=' parameter

CC: Tony Luck <tony.luck@intel.com>
CC: Fenghua Yu <fenghua.yu@intel.com>
CC: linux-ia64@vger.kernel.org
CC: linux-kernel@vger.kernel.org
Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>