nvme: Initial work on conforming to QEMU coding style
nvme: renamed LNVME/lnvme => LNVM/lnvm
nvme: added build checks for LnvmIdCtrl and LnvmIdChannel

The LightNVM standard dictates that the responses of identify and
identify-channel must return exactly 4K - the LnvmIdCtrl and
LnvmIdChannel structs are padded to ensure they comply with this.
nvme: rewrote lnvme feature_set function to use QEMU bitops
nvme: cleanups & rewrite LightNVM channels & partitioning

Various code cleanups, including forgotten conversions of CPU-type
variables to LE byte order as mandated by LightNVM standard.
Rewrote partitioning & initialisation of LightNVM such that LNVM
channels report the LBA range they are responsible for and that
these changes as NS's are formatted.