openrisc: include l.swa in check for write data pagefault

During page fault handling we check the last instruction to understand
if the fault was for a read or for a write.  By default we fall back to
read.  New instructions were added to the openrisc 1.1 spec for an
atomic load/store pair (l.lwa/l.swa).

This patch adds the opcode for l.swa (0x33) allowing it to be treated as
a write operation.

Signed-off-by: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
[shorne@gmail.com: expanded a bit on the comment]
Signed-off-by: Stafford Horne <shorne@gmail.com>

arch/openrisc/kernel/entry.S

@@ -264,7 +264,7 @@ EXCEPTION_ENTRY(_data_page_fault_handler)
 	l.srli  r6,r6,26                   // check opcode for write access
 #endif
 
-	l.sfgeui r6,0x34		   // check opcode for write access
+	l.sfgeui r6,0x33		   // check opcode for write access
 	l.bnf   1f
 	l.sfleui r6,0x37
 	l.bnf   1f