[TG3]: Speed up SRAM access (2nd version)

Speed up SRAM read and write functions if possible by using MMIO
instead of config. cycles. With this change, the post reset signature
done at the end of D3 power change must now be moved before the D3
power change.

IBM reported a problem on powerpc blades during ethtool self test that
was caused by the memory test taking excessively long. Config.  cycles
are very slow on powerpc and the memory test can take more than 10
seconds to complete using config. cycles.

David Miller informed me that an earlier version of the patch caused
problems on sparc64 systems with built-in tg3 chips. This version
fixes the problem by excluding all SUN built-in tg3 chips from doing
MMIO SRAM access.

TG3_FLAG_EEPROM_WRITE_PROT is also set unconditionally when
TG3_FLG2_SUN_570X is set. This should be sane as all SUN chips are
built-in and do not require Vaux switching.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/tg3.h

@@ -2171,6 +2171,7 @@ struct tg3 {
 #define TG3_FLAG_PCIX_MODE		0x00020000
 #define TG3_FLAG_PCI_HIGH_SPEED		0x00040000
 #define TG3_FLAG_PCI_32BIT		0x00080000
+#define TG3_FLAG_SRAM_USE_CONFIG	0x00100000
 #define TG3_FLAG_SERDES_WOL_CAP		0x00400000
 #define TG3_FLAG_JUMBO_RING_ENABLE	0x00800000
 #define TG3_FLAG_10_100_ONLY		0x01000000