[renesas:topic/rcar-gen3-z-clk-v3 2/6] rcar-gen3-cpg.c:undefined reference to `__ffsdi2'

[kbuild test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/horms/renesas.git 
topic/rcar-gen3-z-clk-v3
head:   4b41ea6e92cdc7fce15ba99b02c40938a134cff7
commit: fda8dbe29dd1f04b61c443147a106962cf5d3f14 [2/6] clk: renesas: rcar-gen3: 
Add Z2 clock divider support
config: i386-allmodconfig (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        git checkout fda8dbe29dd1f04b61c443147a106962cf5d3f14
        # save the attached .config to linux build tree
        make ARCH=i386 

All errors (new ones prefixed by >>):

   drivers/clk/renesas/rcar-gen3-cpg.o: In function `cpg_z_clk_set_rate':
>> rcar-gen3-cpg.c:(.text+0x289): undefined reference to `__ffsdi2'

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