nios2: use builtin functions for control registers access

The commit 51926d5ee0be029fb45f10f42756df97279f8ad3
  COMMON: Use __stringify() instead of rest of implementations
forgot to update the wrctl funtion, and causes compilation error.

But there are builtin functions for control registers access in
nios2 comipiler. It is convenient to use them instead.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Cc: Marek Vasut <marex@denx.de>
1 file changed