app/testpmd: fix name of bitrate library in meson build

app/testpmd: fix name of bitrate library in meson build

The bitrate library in DPDK is actually in a "bitratestats" directory,
so that is used by meson for the macro and library name.
Therefore, we need to update references to RTE_LIBRTE_BITRATE to
RTE_LIBRTE_BITRATESTATS in testpmd to have it found. Rather than
supporting both defines, since make is being removed, we can just
replace all instances of the former define with the latter.

To ensure testpmd links ok when this is done, we also need to add
bitratestats to the list of library dependencies.

Fixes: 5b9656b157d3 ("lib: build with meson")
Cc: stable@dpdk.org
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Tested-by: Wei Ling <weix.ling@intel.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>