IB/mthca: Use an enum for HCA page size

Use a named enum for the HCA's internal page size, rather than having
magic values of 4096 and shifts by 12 all over the code.  Also, fix
one minor bug in EQ handling: only one HCA page is mapped to the HCA
during initialization, but a full kernel page is unmapped during
cleanup.  This might cause problems when PAGE_SIZE != 4096.

Signed-off-by: Ishai Rabinovitz <ishai@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/hw/mthca/mthca_memfree.h

@@ -45,6 +45,12 @@
 	((256 - sizeof (struct list_head) - 2 * sizeof (int)) /		\
 	 (sizeof (struct scatterlist)))
 
+enum {
+	MTHCA_ICM_PAGE_SHIFT	= 12,
+	MTHCA_ICM_PAGE_SIZE	= 1 << MTHCA_ICM_PAGE_SHIFT,
+	MTHCA_DB_REC_PER_PAGE	= MTHCA_ICM_PAGE_SIZE / 8
+};
+
 struct mthca_icm_chunk {
 	struct list_head   list;
 	int                npages;
@@ -131,10 +137,6 @@ static inline unsigned long mthca_icm_size(struct mthca_icm_iter *iter)
 	return sg_dma_len(&iter->chunk->mem[iter->page_idx]);
 }
 
-enum {
-	MTHCA_DB_REC_PER_PAGE = 4096 / 8
-};
-
 struct mthca_db_page {
 	DECLARE_BITMAP(used, MTHCA_DB_REC_PER_PAGE);
 	__be64    *db_rec;