[coreboot] [patch]: a little error is fixed.

[Bao, Zheng]

Modify it based on the RPR. 5.7.7. Switching GPPSB Configuration By
Register Programming.

Signed-off-by: Zheng Bao

Index: src/southbridge/amd/rs690/rs690_pcie.c
===================================================================
--- src/southbridge/amd/rs690/rs690_pcie.c	(revision 469)
+++ src/southbridge/amd/rs690/rs690_pcie.c	(working copy)
@@ -148,7 +148,7 @@
    /* waits until SB has trained to L0, poll for bit0-5 = 0x10 */
    do {
    	reg = nbpcie_p_read_index(sb_dev, PCIE_LC_STATE0);
-		reg &= 0x1f;	/* remain LSB 5 bits */
+		reg &= 0x3f;	/* remain LSB [5:0] bits */
    } while (LC_STATE_RECONFIG_GPPSB != reg);

/* ensures that virtual channel negotiation is completed. poll
for bit1 = 0 */