i2c: algo-bit: declare i2c_bit_quirk_no_clk_stretch as static

i2c_bit_quirk_no_clk_stretch is used in i2c-algo-bit.c only, so
declare it as static.

Signed-off-by: Michele Curti <michele.curti@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>