[PATCH] remove duplicated defines from ide.h

[trivia] Remove duplicated defines of PRD_BYTES and PRD_ENTRIES.

include/linux/ide.h

@@ -227,25 +227,6 @@ typedef unsigned char	byte;	/* used everywhere */
 #define PRD_BYTES       8
 #define PRD_ENTRIES     (PAGE_SIZE / (2 * PRD_BYTES))
 
-/*
- * Our Physical Region Descriptor (PRD) table should be large enough
- * to handle the biggest I/O request we are likely to see.  Since requests
- * can have no more than 256 sectors, and since the typical blocksize is
- * two or more sectors, we could get by with a limit of 128 entries here for
- * the usual worst case.  Most requests seem to include some contiguous blocks,
- * further reducing the number of table entries required.
- *
- * The driver reverts to PIO mode for individual requests that exceed
- * this limit (possible with 512 byte blocksizes, eg. MSDOS f/s), so handling
- * 100% of all crazy scenarios here is not necessary.
- *
- * As it turns out though, we must allocate a full 4KB page for this,
- * so the two PRD tables (ide0 & ide1) will each get half of that,
- * allowing each to have about 256 entries (8 bytes each) from this.
- */
-#define PRD_BYTES	8
-#define PRD_ENTRIES	(PAGE_SIZE / (2 * PRD_BYTES))
-
 /*
  * Some more useful definitions
  */