net: remove comments that mention obsolete __SLOW_DOWN_IO

The only remaining definitions of __SLOW_DOWN_IO (for alpha and ia64) do
nothing, and the only mentions in networking are in comments.  Remove these
mentions.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/atm/nicstarmac.c

@@ -14,11 +14,6 @@ typedef void __iomem *virt_addr_t;
 
 #define CYCLE_DELAY 5
 
-/*
-   This was the original definition
-#define osp_MicroDelay(microsec) \
-    do { int _i = 4*microsec; while (--_i > 0) { __SLOW_DOWN_IO; }} while (0)
-*/
 #define osp_MicroDelay(microsec) {unsigned long useconds = (microsec); \
                                   udelay((useconds));}
 /*

drivers/net/ethernet/dec/tulip/winbond-840.c

@@ -474,8 +474,6 @@ static int w840_probe1(struct pci_dev *pdev, const struct pci_device_id *ent)
    No extra delay is needed with 33Mhz PCI, but future 66Mhz access may need
    a delay.  Note that pre-2.0.34 kernels had a cache-alignment bug that
    made udelay() unreliable.
-   The old method of using an ISA access as a delay, __SLOW_DOWN_IO__, is
-   deprecated.
 */
 #define eeprom_delay(ee_addr)	ioread32(ee_addr)
 

drivers/net/ethernet/natsemi/natsemi.c

@@ -989,8 +989,6 @@ static int natsemi_probe1(struct pci_dev *pdev, const struct pci_device_id *ent)
    No extra delay is needed with 33Mhz PCI, but future 66Mhz access may need
    a delay.  Note that pre-2.0.34 kernels had a cache-alignment bug that
    made udelay() unreliable.
-   The old method of using an ISA access as a delay, __SLOW_DOWN_IO__, is
-   deprecated.
 */
 #define eeprom_delay(ee_addr)	readl(ee_addr)