IB/hfi1: Remove redundant sysfs irq affinity entry

The IRQ affinity entry is not needed after the irq notifier patch has been
added to the hfi1 driver.
The irq affinity settings for SDMA engine should be set using the standard
/proc/irq/<N>/ interface.

Reviewed-by: Jianxin Xiong <jianxin.xiong@intel.com>
Signed-off-by: Tadeusz Struk <tadeusz.struk@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>