package/nodejs: fixed comment for mips soft float

nodejs is only selected for mips hard float however the comment is
displayed for hard and soft float.  Correct this by adding the missing
!BR2_MIPS_SOFT_FLOAT to the comment.

Signed-off-by: Martin Bark <martin@barkynet.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>