__bad_udelay is specifically designed on ARM to fail when udelay is
called in a bad way. arch/arm/include/asm/delay.h has this to say
about __bad_udelay:
/*
* This function intentionally does not exist; if you see references to
* it, it means that you're calling udelay() with an out of range value.
*
* With currently imposed limits, this means that we support a max delay
* of 2000us. Further limits: HZ<=1000 and bogomips<=3355
*/
extern void __bad_udelay(void);
Solution is to replace udelay by a mdelay and udelay with value less than 2000