Missing type declaration prefetch_buffer.sv

Created by: timsaxe

Synopsys dc_compiler reports:

Compiling source file ../../ips/cv32e40p/./rtl/cv32e40p_prefetch_buffer.sv Warning: ../../ips/cv32e40p/./rtl/cv32e40p_prefetch_buffer.sv:120: the undeclared symbol 'fifo_empty' assumed to have the default net type, which is 'wire'. (VER-936) Warning: ../../ips/cv32e40p/./rtl/cv32e40p_prefetch_buffer.sv:140: the undeclared symbol 'fifo_full' assumed to have the default net type, which is 'wire'. (VER-936) Presto compilation completed successfully.

I don;t know if this conforms to the style guide, but explicit type declaration is preferable.