CONFIG_SYS_CLK_FREQ: Consistently be static or get_board_sys_clk()

This CONFIG option is used in one of two ways.  The first way is that it
is defined to a static value, of an unsigned long size.  The second way
is that it is defined to something, typically a function, to determine
this value at run time.

However, in a few cases that function returns a static value.  Change
that to using the static value directly.

In the case of using something at run time, convert everything to using
a function of the same name and prototype.  This will allow for further
cleanups.

Finally, we have a few cases where the function is just not used, so
drop it.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/board/freescale/p2041rdb/p2041rdb.c b/board/freescale/p2041rdb/p2041rdb.c
index 4ece1e6..894fe8e 100644
--- a/board/freescale/p2041rdb/p2041rdb.c
+++ b/board/freescale/p2041rdb/p2041rdb.c
@@ -148,7 +148,7 @@
 	return 0;
 }
 
-unsigned long get_board_sys_clk(unsigned long dummy)
+unsigned long get_board_sys_clk(void)
 {
 	u8 sysclk_conf = CPLD_READ(sysclk_sw1);