linuxkpi: Resolve duplicate global symbol name to fix LINT kernel build.

seq_printf() is defined in both spl_procfs_list.c and linux_seq_file.c .
Fix this by renaming the LinuxKPI ones and use macros to invoke the
correct function.

Reported by: jfree@
Differential Revision: https://reviews.freebsd.org/D35883
MFC after: 1 week
Sponsored by: NVIDIA Networking