Replace open coded field decoding with libnvme's getters

[igaw]

Ideally, the nvme-print code would be updated with something like

 static void stdout_id_ctrl_sanicap(__le32 ctrl_sanicap)
 {
        __u32 sanicap = le32_to_cpu(ctrl_sanicap);
-       __u32 rsvd4 = (sanicap & 0x1FFFFFF0) >> 4;
-       __u32 vers = (sanicap & 0x8) >> 3;
-       __u32 ows = (sanicap & 0x4) >> 2;
-       __u32 bes = (sanicap & 0x2) >> 1;
-       __u32 ces = sanicap & 0x1;
-       __u32 ndi = (sanicap & 0x20000000) >> 29;
-       __u32 nodmmas = (sanicap & 0xC0000000) >> 30;
+       __u32 vers = NVME_CTRL_SANICAP_VERS(sanicap);
+       __u32 nvers = NVME_CTRL_SANICAP_NVERS(sanicap);
+       __u32 ows = NVME_CTRL_SANICAP_OWS(sanicap);
+       __u32 bes = NVME_CTRL_SANICAP_BES(sanicap);
+       __u32 ces = NVME_CTRL_SANICAP_CES(sanicap);
+       __u32 ndi = NVME_CTRL_SANICAP_NDI(sanicap);
+       __u32 nodmmas = NVME_CTRL_SANICAP_NODMMAS(sanicap);

So we don't do the decoding open coded anymore.

Originally posted by @igaw in #3731