Is it legal if I was fired after reporting a manger?

IF you had been fired for reporting a sexist comment, it might well have been illegal: you might have been the victim of illegal retaliation for reporting sexual harassment or discrimination. 
However, based on what you write, that is not what happened: you write that you put your notice in: that is, you quit. You put in your notice because you did not like working the line alone, but your employer has the right to make staffing, shift, etc. assignments: that is, they had the right to have you work the line alone. Therefore, you quit due to the employer doing something which they could do. Quiting in that case is a voluntary separation from employment; it means you were not fired. Even if they cut short your notice period, which an employer may do (2-week notice is a tradition, not a right or obligation), that doesn't change the fact that you gave your notice and quit. 
Again, since you provided notice, your employer did not terminate you; therefore, they did not take action against you and you have no claim against them. 
Moreover, you write that they fired the manager who made the comment: that shows they took the report seriously and did what they were supposed to, which will reinforce the fact that they did not take improper action here.