Replace M_SUF (M_LN2) with M_MLIT (M_LN2)

According to math-type-macros.h, M_SUF should be used to paste the
suffix used by functions, while M_MLIT is used with macro constants.

	* math/e_exp2_template.c: Replace M_SUF (M_LN2) with M_MLIT (M_LN2).

Signed-off-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>