rcar_flash.yaml: remove "spider" suffix from bl31 and tee filenames

Yocto build now provides generic symlinks "bl31.srec" and "tee.srec"
for all "S4" board variants ("Spider" and "S4SK").

This change updates the YAML config to refer to the generic
filenames, making it compatible with the current deploy behavior.

Signed-off-by: Mykhailo Androsiuk <mykhailo_androsiuk@epam.com>

Author: Mykhailo Androsiuk

rcar_flash/rcar_flash.yaml

@@ -420,7 +420,7 @@ board:
         flash_target: s4_qspi
       bl31:
         flash_target: s4_emmc
-        file: bl31-spider.srec
+        file: bl31.srec
         flash_addr: 0x7000
       bootparam:
         flash_target: s4_qspi
@@ -448,7 +448,7 @@ board:
         flash_addr: 0x40000
       tee:
         flash_target: s4_emmc
-        file: tee-spider.srec
+        file: tee.srec
         flash_addr: 0x7400
       u-boot:
         flash_target: s4_emmc