riscv: sifive/fu540: spl: Rename soc_spl_init()

spl_soc_init() seems to be a better name, as all SPL functions
names start from the spl_ prefix.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Rick Chen <rick@andestech.com>
Reviewed-by: Pragnesh Patel <pragnesh.patel@sifive.com>
Tested-by: Pragnesh Patel <pragnesh.patel@sifive.com>
diff --git a/arch/riscv/include/asm/arch-fu540/spl.h b/arch/riscv/include/asm/arch-fu540/spl.h
index 0c188be..4697279 100644
--- a/arch/riscv/include/asm/arch-fu540/spl.h
+++ b/arch/riscv/include/asm/arch-fu540/spl.h
@@ -9,6 +9,6 @@
 #ifndef _SPL_SIFIVE_H
 #define _SPL_SIFIVE_H
 
-int soc_spl_init(void);
+int spl_soc_init(void);
 
 #endif /* _SPL_SIFIVE_H */