device/dram/ddr2: Add a function to normalize tCLK

Also make most significant bit function accessible outside the scope
of this file.

Change-Id: I3ab39d38a243edddfde8f70ebd23f79ff774e90e
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/18320
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

src/include/device/dram/ddr2.h

@@ -213,6 +213,7 @@ u32 spd_decode_spd_size_ddr2(u8 byte0);
 u32 spd_decode_eeprom_size_ddr2(u8 byte1);
 int spd_decode_ddr2(struct dimm_attr_st *dimm, u8 spd[SPD_SIZE_MAX_DDR2]);
 void dram_print_spd_ddr2(const struct dimm_attr_st *dimm);
-
+void normalize_tck(u32 *tclk);
+u8 spd_get_msbs(u8 c);
 
 #endif /* DEVICE_DRAM_DDR2L_H */