[FMV] Remove features predres and ls64.

[labrinea]

These cannot be detected by reading the ID_AA64ISAR1_EL1 register since their corresponding bitfields are hidden according to the Linux Kernel docs:

https://www.kernel.org/doc/html/latest/arch/arm64/cpu-feature-registers.html

Additionally the instructions that these features enable are unusable from user space (Exception Level 0).

For SPECRES the Arm Architecture Reference Manual says:

In AArch64 state, EL0 access to the System instructions is controlled by:

• When HCR_EL2.{E2H, TGE} is not {1, 1}, SCTLR_EL1.EnRCTX.
• When HCR_EL2.{E2H, TGE} == {1, 1}, SCTLR_EL2.EnRCTX.

For LS64 it says:

• SCTLR_EL1.EnALS, bit [56] : When FEAT_LS64 is implemented: When the Effective value of HCR_EL2.{E2H, TGE} is not {1, 1}, traps execution of an LD64B or ST64B instruction at EL0 to EL1.

• SCTLR_EL1.EnAS0, bit [55] : When FEAT_LS64_ACCDATA is implemented: When the Effective value of HCR_EL2.{E2H, TGE} is not {1, 1}, traps execution of an ST64BV0 instruction at EL0 to EL1.

• SCTLR_EL1.EnASR, bit [54] : When FEAT_LS64_V is implemented: When the Effective value of HCR_EL2.{E2H, TGE} is not {1, 1}, traps execution of an ST64BV instruction at EL0 to EL1.

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[labrinea]

@DanielKristofKiss @andrewcarlotti @Wilco1 @jroelofs @ilinpv

[DanielKristofKiss]

LGTM