powerpc: mpc85xx: Rename _start_e500 symbol to _start

The real entry point is _start_e500. There is no _start symbol at all. So
rename _start_e500 to _start for convension that _start symbol is used as
entry point.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>
diff --git a/doc/README.mpc85xx b/doc/README.mpc85xx
index 8464e7f..3c6ebbd 100644
--- a/doc/README.mpc85xx
+++ b/doc/README.mpc85xx
@@ -45,7 +45,7 @@
 A) defined(CONFIG_SYS_RAMBOOT) i.e. SD, SPI, NAND RAMBOOT & NAND_SPL boot
 
    1) TLB entry to overcome e500 v1/v2 debug restriction
-       Location	  : Label "_start_e500"
+       Location	  : Label "_start"
        TLB Entry  : CONFIG_SYS_PPC_E500_DEBUG_TLB
        EPN -->RPN : CONFIG_SYS_MONITOR_BASE --> CONFIG_SYS_MONITOR_BASE
        Properties : 256K, AS0, I, IPROT
@@ -91,7 +91,7 @@
 B) !defined(CONFIG_SYS_RAMBOOT) i.e. NOR boot
 
    1) TLB entry to overcome e500 v1/v2 debug restriction
-       Location	  : Label "_start_e500"
+       Location	  : Label "_start"
        TLB Entry  : CONFIG_SYS_PPC_E500_DEBUG_TLB
 #if defined(CONFIG_NXP_ESBC)
        EPN -->RPN : CONFIG_SYS_MONITOR_BASE --> CONFIG_SYS_PBI_FLASH_WINDOW