tools/thermal: tmon: fix compilation errors when building statically

tmon fails to build statically with the following error:

$ make LDFLAGS=-static
gcc -O1 -Wall -Wshadow -W -Wformat -Wimplicit-function-declaration -Wimplicit-int -fstack-protector -D VERSION=\"1.0\" -static tmon.o tui.o sysfs.o pid.o   -o tmon -lm -lpanel -lncursesw  -lpthread
tmon.o: In function `tmon_sig_handler':
tmon.c:(.text+0x21): undefined reference to `stdscr'
tmon.o: In function `tmon_cleanup':
tmon.c:(.text+0xb9): undefined reference to `stdscr'
tmon.c:(.text+0x11e): undefined reference to `stdscr'
tmon.c:(.text+0x123): undefined reference to `keypad'
tmon.c:(.text+0x12d): undefined reference to `nocbreak'
tmon.o: In function `main':
tmon.c:(.text+0x785): undefined reference to `stdscr'
tmon.c:(.text+0x78a): undefined reference to `nodelay'
tui.o: In function `setup_windows':
tui.c:(.text+0x131): undefined reference to `stdscr'
tui.c:(.text+0x176): undefined reference to `stdscr'
tui.c:(.text+0x19f): undefined reference to `stdscr'
tui.c:(.text+0x1cc): undefined reference to `stdscr'
tui.c:(.text+0x1ff): undefined reference to `stdscr'
tui.o:tui.c:(.text+0x229): more undefined references to `stdscr' follow
tui.o: In function `show_cooling_device':
[...]

stdscr() and friends are in libtinfo (part of ncurses) so add it to
the libraries that are linked in when compiling tmon to fix it.

Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Javi Merino <javi.merino@arm.com>
Acked-by: Jacob Pan <jacob.jun.pan@linux.intel.com>