arc: get rid of useless CONFIG_SKIP_LOWLEVEL_INIT

Currently there's nothing related to really low-level init on ARC so
CONFIG_SKIP_LOWLEVEL_INIT definition makes no sense.
Signed-off-by: NAlexey Brodkin <abrodkin@synopsys.com>

include/configs/arcangel4.h

@@ -15,8 +15,6 @@
 /*
  * Board configuration
  */
-#define CONFIG_SKIP_LOWLEVEL_INIT	/* U-Boot is in RAM already */
-
 #define CONFIG_ARCH_EARLY_INIT_R
 
 /*

include/configs/axs101.h

@@ -15,8 +15,6 @@
 /*
  * Board configuration
  */
-#define CONFIG_SKIP_LOWLEVEL_INIT	/* U-Boot is in RAM already */
-
 #define CONFIG_ARCH_EARLY_INIT_R
 
 #define ARC_FPGA_PERIPHERAL_BASE	0xE0000000