Fix /wi by removing wrong fallthrough

[ret2libc]

Your checklist for this pull request

• I've read the guidelines for contributing to this repository
• I made sure to follow the project's coding style
• I've documented or updated the documentation of every function and struct this PR changes. If not so I've explained why.
• I've added tests that prove my fix is effective or that my feature works (if possible)
• I've updated the rizin book with the relevant information (if needed)

Detailed description

/wi was falling through the switch case and it was not accepting the input correctly. Fix this by breaking at the end of the '/w' case so that the search can begin.

Test plan

See test.

Closing issues

Closes #3633

[XVilka]

We really should finish conversion to rzshell: #2212

[XVilka]

Just for the record, btw, this kind of search should employ the string search from librz/include/rz_util/rz_str_search.h cc @wargio, because librz/search/keyword.c seems to reimplement the thing again...