Enable PCIe slot bifurcation using HX keyword

    -Update the PCIe config code to check the contents
     of the HX keyword attribute when determining the
     lane configuration.

     The HX keyword was defined to describe the lane
     configuration for a specific PCIe slot.
     It is generally stored in the VPD data of a PCIe card
     where it is read by the FSP. If the HX keyword
     data is populated, the FSP will then update the
     PEC_PCIE_HX_KEYWORD_DATA attribute for the
     PCIe slot the card is installed in. Once hostboot
     reads the HX keyword it will determine the correct
     lane configuration and adjust the IOP configuration
     attributes for the hardware procedure, p9_pcie_scominit,
     to consume.

Change-Id: I10b1fcc84aacf3caf835e3cc9fffd1350cd30935
RTC:189286
Reviewed-on: http://rchgit01.rchland.ibm.com/gerrit1/59113
Tested-by: Jenkins Server <pfd-jenkins+hostboot@us.ibm.com>
Reviewed-by: Daniel M. Crowell <dcrowell@us.ibm.com>

src/include/usr/isteps/istep_reasoncodes.H

@@ -64,6 +64,7 @@ namespace ISTEP
         MOD_FREQ_ATTR_DATA                                = 0x21,
         MOD_SMP_WRAP_PROC_IOVALID                         = 0x22,
         MOD_APPLY_HCODE_GEN_CPU_REGS                      = 0x23,
+        MOD_GET_LANEMASK_FROM_HX_KEYWORD                  = 0x24,
     };
 
     /**
@@ -133,6 +134,7 @@ namespace ISTEP
         RC_SLAVE_GET_SBE_BOOT_SEEPROM_FAIL       = ISTEP_COMP_ID | 0x49,
         RC_LINK_TRAIN_ERRORS_FROM_HWP            = ISTEP_COMP_ID | 0x4A,
         RC_RISK_LEVEL_TOO_LOW                    = ISTEP_COMP_ID | 0x4B,
+        RC_INVALID_HX_KEYWORD_DATA               = ISTEP_COMP_ID | 0x4C,
     };
 
 };