fix(bluetooth-pbap-binding.c): Remove -Wformat warning

fix(bluetooth-pbap-binding.c): Remove -Wformat warning

agl-service-bluetooth/agl-service-bluetooth-pbap/binding/
bluetooth-pbap-binding.c:173:13: warning: format ‘%ld’ expects argument
of type ‘long int’, but argument 7 has type ‘size_t’
{aka ‘unsigned int’} [-Wformat=]
AFB_ERROR("Read only %ld/%ld bytes from %s", n, size, filename);
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  ~
agl-service-bluetooth/agl-service-bluetooth-pbap/binding/
bluetooth-pbap-binding.c:173:13: warning: format ‘%ld’ expects argument
of type ‘long int’, but argument 8 has type ‘size_t’ {aka ‘unsigned int’}
[-Wformat=]

Bug-AGL: SPEC-2422

Change-Id: I90504163278b3bbd415b73021bd32eaa2a759572
Signed-off-by: Li Xiaoming <lixm.fnst@cn.fujitsu.com>