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/t102xrdb/README b/board/freescale/t102xrdb/README
index dde3f8c..84deb95 100644
--- a/board/freescale/t102xrdb/README
+++ b/board/freescale/t102xrdb/README
@@ -39,7 +39,7 @@
   - One QSGMII interface
   - Four SGMII interface supporting 1000 Mbps
   - Three SGMII interfaces supporting up to 2500 Mbps
-  - 10GbE XFI or 10Base-KR interface
+  - 10GBase-R or 10Base-KR interface
 - Additional peripheral interfaces
   - Two USB 2.0 controllers with integrated PHY
   - SD/eSDHC/eMMC