Runtime error when running mode ON and ONB with ls larger than ns

[Ping-Hsuan]

Currently, in NekROM ns is set to ls by default (it is set in subroutine mor_init_params of rom.f)

However, in mor_set_params_par, if one is using mode 'ON' or mode 'ONB,' the code will set nns variable, which will be used in later when loading uk arrays, by reading the value in ops/ns and raise an error if the read value is less than ns. Because ns is set to be ls by default, if users set ls to be larger than ns (which is valid), the code yields a runtime error: ms less than ns...

One can bypass this issue by explicitly setting ns in the par file. However, we should fix this so that ls can be larger than ns.