Revert r236529, re-enabling verification of the flashed content as

the underlying problem was dealt with in r237239 (in fact, disabling
verification also actually only made the problem less likely to occur).

sys/dev/flash/at45d.c

@@ -390,7 +390,6 @@ at45d_task(void *arg)
 				berr = EIO;
 				goto out;
 			}
-#ifdef notyet /* May cause physwr to hang for reasons unknown. */
 			if (bp->bio_cmd == BIO_WRITE) {
 				addr = page << sc->pageoffset;
 				txBuf[0] = BUFFER_COMPARE;
@@ -409,7 +408,6 @@ at45d_task(void *arg)
 					goto out;
 				}
 			}
-#endif
 			page++;
 			buf += len;
 			offset = 0;