i2c: stm32f7: remove warning when compiling with W=1

i2c: stm32f7: remove warning when compiling with W=1

Remove the following warning:

drivers/i2c/busses/i2c-stm32f7.c:315:
warning: cannot understand function prototype:
'struct stm32f7_i2c_spec i2c_specs[] =

Replace a comment starting with /** by simply /* to avoid having
it interpreted as a kernel-doc comment.

Fixes: aeb068c57214 ("i2c: i2c-stm32f7: add driver")
Signed-off-by: Alain Volmat <alain.volmat@st.com>
Reviewed-by: Pierre-Yves MORDRET <pierre-yves.mordret@st.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>