plugins/fmcomms2: Fix warnings

Fix the following warnings:
	plugins/fmcomms2.c: In function ‘analyse_wavefile’:
	plugins/fmcomms2.c:289:31: warning: initialization from incompatible pointer type [enabled by default]
	plugins/fmcomms2.c:290:28: warning: initialization from incompatible pointer type [enabled by default]

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
plugins/debug: Make sure field precision specifiers are int

Make sure to cast the type of the field precision specifier to int, otherwise
bad things will happen on 64-bit machines. Also fixes the following warnings:

plugins/debug.c: In function ‘element_substr’:
plugins/debug.c:154:3: warning: field precision specifier ‘.*’ expects argument of type ‘int’, but argument 3 has type ‘size_t’ [-Wformat]
plugins/debug.c: In function ‘scan_elements_sort’:
plugins/debug.c:252:4: warning: field precision specifier ‘.*’ expects argument of type ‘int’, but argument 3 has type ‘long int’ [-Wformat]
plugins/debug.c: In function ‘scanel_read_clicked’:
plugins/debug.c:341:4: warning: field precision specifier ‘.*’ expects argument of type ‘int’, but argument 3 has type ‘long int’ [-Wformat]
plugins/debug.c:355:6: warning: field precision specifier ‘.*’ expects argument of type ‘int’, but argument 3 has type ‘long int’ [-Wformat]
plugins/debug.c: In function ‘debug_device_list_cb’:
plugins/debug.c:461:5: warning: field precision specifier ‘.*’ expects argument of type ‘int’, but argument 3 has type ‘long int’ [-Wformat]
plugins/debug.c:464:5: warning: field precision specifier ‘.*’ expects argument of type ‘int’, but argument 3 has type ‘long int’ [-Wformat]

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>