How to enable 'CONFIG_COMMON_CLK' ?

Hello, L4 Hackers :-)

I'm trying to build L4 Linux with added option of MMC device driver.

When I've tried to compile L4 Linux , I've failed it with error log such 
as..
==============
drivers/built-in.o: In function `sdhci_pltfm_clk_get_max_clock':
/home/taeung/test/source/l4linux/drivers/mmc/host/sdhci-pltfm.c:43: 
undefined reference to `clk_get_rate'
make[1]: *** [vmlinux] Error 1
make: *** [sub-make] Error 2
==============

After I saw the log , I've guessed the  cause is that 
'drivers/clk/clk.c' was not built.
So, I must enable  'CONFIG_COMMON_CLK' , to build 'drivers/clk/clk.c'

How to enable 'CONFIG_COMMON_CLK' ?

For reference, I've tried to compile L4 Linux with options as follows..
===================================
        --- MMC/SD/SDIO card support
[ ]   MMC debugging
[*]   Assume MMC/SD cards are non-removable (DANGEROUS)
[ ]   MMC host clock gating

       *** MMC/SD/SDIO Card Drivers ***
<*>   MMC block device driver
(8)     Number of minors per block device
[*]     Use bounce buffer for simple hosts
< >   SDIO UART/GPS class support
< >   MMC host test driver

       *** MMC/SD/SDIO Host Controller Drivers ***
< >   ARM AMBA Multimedia Card Interface support
-*-   Secure Digital Host Controller Interface support
-*-   SDHCI platform and OF driver helper
<*>   Marvell MMP2 SD Host Controller support (PXAV3)
< >   Marvell PXA9XX SD Host Controller support (PXAV2)
< >   Synopsys DesignWare Memory Card Interface
====================================


-Taeung -