net: replace the "xfi" phy-mode with "10gbase-r"

As part of the effort of making U-Boot work with the same device tree as
Linux, there is an issue with the "xfi" phy-mode. To be precise, in
Linux there was a discussion (for those who have time to read:
https://lore.kernel.org/netdev/1576768881-24971-2-git-send-email-madalin.bucur@oss.nxp.com/)

which led to a patch:
https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=c114574ebfdf42f826776f717c8056a00fa94881

TL;DR: "xfi" was standardized in Linux as "10gbase-r".

This patch changes the relevant occurrences in U-Boot to use "10gbase-r"
instead of "xfi" wherever applicable.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
diff --git a/board/freescale/ls1046aqds/README b/board/freescale/ls1046aqds/README
index b8fa326..d646901 100644
--- a/board/freescale/ls1046aqds/README
+++ b/board/freescale/ls1046aqds/README
@@ -18,7 +18,7 @@
       - SGMII, SGMII 2.5
       - QSGMII
       - SATA 3.0
-      - XFI
+      - 10GBase-R
  - DDR Controller
      - 8GB 64bits DDR4 SDRAM. Support rates of up to 2133MT/s
  -IFC/Local Bus