soc/sifive/fu540: Remove PLL parameters from sdram.c

These parameters are not used and not necessary in sdram.c, because the
DDR PLL is configured in clock.c.

Change-Id: I8060bd21e05765cedf7bdabc28052c32774f9ca1
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-on: https://review.coreboot.org/28710
Reviewed-by: Philipp Hug <philipp@hug.cx>
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/sifive/fu540/sdram.c

@@ -25,8 +25,6 @@
 #include "ddrregs.h"
 
 #define DDR_SIZE  (8UL * 1024UL * 1024UL * 1024UL)
-#define DDRCTLPLL_F 55
-#define DDRCTLPLL_Q 2
 
 void sdram_init(void)
 {