ena: Add reset reason for corrupted TX cdescs

TX completion descriptors may sometimes contain errors due
to corruption. Upon identifying such a case, the driver will
trigger a reset with an explicit reset reason
ENA_REGS_RESET_TX_DESCRIPTOR_MALFORMED.

Approved by: cperciva (mentor)
Sponsored by: Amazon, Inc.

(cherry picked from commit 38727218460008a500fbc18f08c90082ed678895)