conf: machine: am64xx-evm: Switch to SR2.0 HS-FS build by default

AM64x devices will only be available as SR2.0 HS-FS. Set this as the
default type provided by the SDK. To allow SR2.0 HS-SE to continue to
boot, like we did with GP, we add an extra machine to build SR2.0 HS-SE
SYSFW. To use on SR2.0 HS-SE boards simply switch out the SYSFW image:

$ cd /mnt/sd-card/boot
$ mv tiboot3-am64x_sr2-hs-evm.bin tiboot3.bin

Signed-off-by: Andrew Davis <afd@ti.com>
Signed-off-by: Ryan Eatmon <reatmon@ti.com>

conf/multiconfig/k3r5-sr2-hs-fs.conf

@@ -0,0 +1,3 @@
+require k3r5-sr2.conf
+
+MACHINE_append = "-hs-fs"

conf/multiconfig/k3r5-sr2-hs-se.conf

@@ -1,3 +1,3 @@
-require k3r5.conf
+require k3r5-sr2.conf
 
 MACHINE_append = "-hs-se"