xtensa: Remove local no-op dram_init_banksize()

When this no-op dram_init_banksize() is removed, the weak default will
be used instead, which correctly sets the bi_dram[] banksize values.

Signed-off-by: Stefan Roese <sr@denx.de>
Reviewed-by: Ovidiu Panait <ovidiu.panait@windriver.com>
diff --git a/board/cadence/xtfpga/xtfpga.c b/board/cadence/xtfpga/xtfpga.c
index 4b49b6e..5811c43 100644
--- a/board/cadence/xtfpga/xtfpga.c
+++ b/board/cadence/xtfpga/xtfpga.c
@@ -49,11 +49,6 @@
 	return 0;
 }
 
-int dram_init_banksize(void)
-{
-	return 0;
-}
-
 int board_postclk_init(void)
 {
 	/*