CONFIG_NR_DRAM_BANKS: Remove unreferenced code as its always defined

Since commit 86cf1c8285 ("configs: Migrate CONFIG_NR_DRAM_BANKS") &
commit 999a772d9f ("Kconfig: Migrate CONFIG_NR_DRAM_BANKS"),
CONFIG_NR_DRAM_BANKS is always defined with a value (4 is default).
It makes no sense to still carry code that is guarded with
"#ifndef CONFIG_NR_DRAM_BANKS" (and similar). This patch removes
all these unreferenced code paths.

Signed-off-by: Stefan Roese <sr@denx.de>
Reviewed-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

board/xilinx/zynqmp/zynqmp.c

@@ -423,10 +423,8 @@ int dram_init(void)
 #else
 int dram_init_banksize(void)
 {
-#if defined(CONFIG_NR_DRAM_BANKS)
 	gd->bd->bi_dram[0].start = CONFIG_SYS_SDRAM_BASE;
 	gd->bd->bi_dram[0].size = get_effective_memsize();
-#endif
 
 	mem_map_fill();